Fixed background color warning in UITableViewHeaderFooterView (#417)

* Add prepareCellForSkeleton for UITableView and UICollectionView

* Update README to add collectionSkeletonView(_ skeletonView: UICollectionView, prepareCellForSkeleton cell: UICollectionViewCell, at indexPath: IndexPath)

* Update README.md

Co-authored-by: Juanpe Catalán <juanpecm@gmail.com>

.github/workflows/CD.yml

@@ -0,0 +1,64 @@
+name: CD
+
+on:
+  pull_request:
+    branches: [main]
+    types: [closed]
+        
+jobs:
+  release_version:
+    if: github.event.pull_request.milestone == null && github.event.pull_request.merged == true
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+          
+      - name: Setup fastlane
+        run: brew install fastlane
+            
+      - name: Publish release
+        id: publish_release
+        uses: release-drafter/release-drafter@v5
+        with: 
+          publish: true
+        env:
+           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Update podspec 
+        run: fastlane bump_version next_version:${{ steps.publish_release.outputs.tag_name }}
+
+      - name: Commit changes
+        uses: stefanzweifel/git-auto-commit-action@v4
+        with:
+          branch: 'main'
+          commit_message: 'Bump version ${{ steps.publish_release.outputs.tag_name }}'
+        env:
+         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}      
+
+      - name: Deploy to Cocoapods
+        env:
+          COCOAPODS_TRUNK_TOKEN: ${{ secrets.COCOAPODS_TRUNK_TOKEN }}
+        run: |
+          set -eo pipefail
+          pod lib lint --allow-warnings
+          pod trunk push --allow-warnings    
+
+      - name: Communicate on PR released
+        uses: unsplash/comment-on-pr@master
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          msg: |
+            Congratulations! 🎉 This was released as part of [SkeletonView ${{ steps.publish_release.outputs.tag_name }}](${{ steps.publish_release.outputs.html_url }}) 🚀  
+
+      - name: Tweet the release
+        uses: ethomson/send-tweet-action@v1
+        with:
+          consumer-key: ${{ secrets.TWITTER_CONSUMER_API_KEY }}
+          consumer-secret: ${{ secrets.TWITTER_CONSUMER_API_SECRET }}
+          access-token: ${{ secrets.TWITTER_ACCESS_TOKEN }}
+          access-token-secret: ${{ secrets.TWITTER_ACCESS_TOKEN_SECRET }}
+          status: |
+            🎉 New release ${{ steps.publish_release.outputs.tag_name }} is out 🚀
+
+            Check out all the changes here: 
+            ${{ steps.publish_release.outputs.html_url }} 

Example/CollectionView/ViewController.swift

@@ -174,6 +174,12 @@ extension ViewController: SkeletonCollectionViewDataSource {
     func collectionSkeletonView(_ skeletonView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
         return 10
     }
+
+    func collectionSkeletonView(_ skeletonView: UICollectionView, skeletonCellForItemAt indexPath: IndexPath) -> UICollectionViewCell? {
+        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionViewCell", for: indexPath) as? CollectionViewCell
+        cell?.isSkeletonable = indexPath.row != 0
+        return cell
+    }
     
     // MARK: - UICollectionViewDataSource
     
@@ -184,6 +190,10 @@ extension ViewController: SkeletonCollectionViewDataSource {
     func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
         let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionViewCell", for: indexPath) as! CollectionViewCell
         return cell
-        
+    }
+
+    func collectionSkeletonView(_ skeletonView: UICollectionView, prepareCellForSkeleton cell: UICollectionViewCell, at indexPath: IndexPath) {
+        let cell = cell as? CollectionViewCell
+        cell?.isSkeletonable = indexPath.row != 0
     }
 }

Example/TableView/ViewController.swift

@@ -183,6 +183,17 @@ extension ViewController: SkeletonTableViewDataSource {
         cell.label1.text = "cell -> \(indexPath.row)"
         return cell
     }
+    
+    func collectionSkeletonView(_ skeletonView: UITableView, skeletonCellForRowAt indexPath: IndexPath) -> UITableViewCell? {
+        let cell = skeletonView.dequeueReusableCell(withIdentifier: "CellIdentifier", for: indexPath) as? Cell
+        cell?.textField.isHidden = indexPath.row == 0
+        return cell
+    }
+
+    func collectionSkeletonView(_ skeletonView: UITableView, prepareCellForSkeleton cell: UITableViewCell, at indexPath: IndexPath) {
+        let cell = cell as? Cell
+        cell?.textField.isHidden = indexPath.row == 0
+    }
 }
 
 extension ViewController: SkeletonTableViewDelegate {

README.md

@@ -169,19 +169,16 @@ If you want to show the skeleton in a ```UITableView```, you need to conform to
 
 ``` swift
 public protocol SkeletonTableViewDataSource: UITableViewDataSource {
-    func numSections(in collectionSkeletonView: UITableView) -> Int
+    func numSections(in collectionSkeletonView: UITableView) -> Int // Default: 1
     func collectionSkeletonView(_ skeletonView: UITableView, numberOfRowsInSection section: Int) -> Int
     func collectionSkeletonView(_ skeletonView: UITableView, cellIdentifierForRowAt indexPath: IndexPath) -> ReusableCellIdentifier
+    func collectionSkeletonView(_ skeletonView: UITableView, skeletonCellForRowAt indexPath: IndexPath) -> UITableViewCell? // Default: nil
+    func collectionSkeletonView(_ skeletonView: UITableView, prepareCellForSkeleton cell: UITableViewCell, at indexPath: IndexPath)
 }
 ```
 As you can see, this protocol inherits from ```UITableViewDataSource```, so you can replace this protocol with the skeleton protocol.
 
-This protocol has a default implementation:
-
-``` swift
-func numSections(in collectionSkeletonView: UITableView) -> Int
-// Default: 1
-```
+This protocol has a default implementation for some methods. For example, the number of rows for each section is calculated in runtime:
 
 ``` swift
 func collectionSkeletonView(_ skeletonView: UITableView, numberOfRowsInSection section: Int) -> Int
@@ -191,20 +188,33 @@ func collectionSkeletonView(_ skeletonView: UITableView, numberOfRowsInSection s
 
 > 📣 **IMPORTANT!** 
 >
-> If you return `SkeletonCollectionDataSource.automaticNumberOfRows` in the above method, it acts like the default behavior (i.e. it calculates how many cells needed to populate the whole tableview).
+> If you return `UITableView.automaticNumberOfSkeletonRows` in the above method, it acts like the default behavior (i.e. it calculates how many cells needed to populate the whole tableview).
 
 There is only one method you need to implement to let Skeleton know the cell identifier. This method doesn't have default implementation:
- ``` swift
- func collectionSkeletonView(_ skeletonView: UITableView, cellIdentifierForRowAt indexPath: IndexPath) -> ReusableCellIdentifier
- ```
-
-**Example**
  ``` swift
  func collectionSkeletonView(_ skeletonView: UITableView, cellIdentifierForRowAt indexPath: IndexPath) -> ReusableCellIdentifier {
     return "CellIdentifier"
 }
  ```
  
+ By default, the library dequeues the cells from each indexPath, but you can also do this if you want to make some changes before the skeleton appears:
+ ``` swift
+ func collectionSkeletonView(_ skeletonView: UITableView, skeletonCellForRowAt indexPath: IndexPath) -> UITableViewCell? {
+     let cell = skeletonView.dequeueReusableCell(withIdentifier: "CellIdentifier", for: indexPath) as? Cell
+     cell?.textField.isHidden = indexPath.row == 0
+     return cell
+ }
+ ```
+ 
+If you prefer to leave the deque part to the library you can configure the cell using this method:
+ ``` swift
+ func collectionSkeletonView(_ skeletonView: UITableView, prepareCellForSkeleton cell: UITableViewCell, at indexPath: IndexPath) {
+     let cell = cell as? Cell
+     cell?.textField.isHidden = indexPath.row == 0
+ }
+ ```
+
+ 
 Besides, you can skeletonize both the headers and footers. You need to conform to `SkeletonTableViewDelegate` protocol.
 
 ```swift
@@ -232,10 +242,12 @@ For `UICollectionView`, you need to conform to `SkeletonCollectionViewDataSource
 
 ``` swift
 public protocol SkeletonCollectionViewDataSource: UICollectionViewDataSource {
-    func numSections(in collectionSkeletonView: UICollectionView) -> Int // default: 1
+    func numSections(in collectionSkeletonView: UICollectionView) -> Int  // default: 1
     func collectionSkeletonView(_ skeletonView: UICollectionView, numberOfItemsInSection section: Int) -> Int
     func collectionSkeletonView(_ skeletonView: UICollectionView, cellIdentifierForItemAt indexPath: IndexPath) -> ReusableCellIdentifier
     func collectionSkeletonView(_ skeletonView: UICollectionView, supplementaryViewIdentifierOfKind: String, at indexPath: IndexPath) -> ReusableCellIdentifier? // default: nil
+    func collectionSkeletonView(_ skeletonView: UICollectionView, skeletonCellForItemAt indexPath: IndexPath) -> UICollectionViewCell?  // default: nil
+    func collectionSkeletonView(_ skeletonView: UICollectionView, prepareCellForSkeleton cell: UICollectionViewCell, at indexPath: IndexPath)
 }
 ```
 
@@ -498,12 +510,30 @@ view.isHiddenWhenSkeletonIsActive = true  // This works only when isSkeletonable
 **Don't modify user interaction when the skeleton is active**
 
 
-By default, user interaction is disabled for skeletonized items, but if you don't want to modify the user interaction indicator when skeleton is active, you can use the `isUserInteractionDisabledWhenSkeletonIsActive` property:
+By default, the user interaction is disabled for skeletonized items, but if you don't want to modify the user interaction indicator when skeleton is active, you can use the `isUserInteractionDisabledWhenSkeletonIsActive` property:
 
 ```swift
 view.isUserInteractionDisabledWhenSkeletonIsActive = false  // The view will be active when the skeleton will be active.
 ```
 
+**Delayed show skeleton**
+
+You can delay the presentation of the skeleton if the views update quickly.
+
+```swift
+func showSkeleton(usingColor: UIColor,
+                  animated: Bool,
+                  delay: TimeInterval,
+                  transition: SkeletonTransitionStyle)
+```
+
+```swift
+func showGradientSkeleton(usingGradient: SkeletonGradient,
+                          animated: Bool,
+                          delay: TimeInterval,
+                          transition: SkeletonTransitionStyle)
+```
+
 **Debug**
 
 To facilitate the debug tasks when something is not working fine. **`SkeletonView`** has some new tools.
@@ -535,9 +565,12 @@ Then, when the skeleton appears, you can see the view hierarchy in the Xcode con
 * tvOS 9.0+
 * Swift 5
 
+## :sweat_smile: Need help
+If you need help about how to use **SkeletonView**, use [Stack Overflow](https://stackoverflow.com/questions/tagged/skeletonview) and tag `skeletonview`.
 
 ## ❤️ Contributing
 This is an open source project, so feel free to contribute. How?
+
 - Open an [issue](https://github.com/Juanpe/SkeletonView/issues/new).
 - Send feedback via [email](mailto://juanpecatalan.com).
 - Propose your own fixes, suggestions and open a pull request with the changes.

SkeletonView.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name         = "SkeletonView"
-  s.version      = "1.17.0"
+  s.version      = "1.19.0"
   s.summary      = "An elegant way to show users that something is happening and also prepare them to which contents he is waiting"
   s.description  = <<-DESC
   Today almost all apps have async processes, as API requests, long runing processes, etc. And while the processes are working, usually developers place a loading view to show users that something is going on.

Sources/Collections/CollectionViews/SkeletonCollectionViewProtocols.swift

@@ -13,20 +13,28 @@ public protocol SkeletonCollectionViewDataSource: UICollectionViewDataSource {
     func collectionSkeletonView(_ skeletonView: UICollectionView, numberOfItemsInSection section: Int) -> Int
     func collectionSkeletonView(_ skeletonView: UICollectionView, cellIdentifierForItemAt indexPath: IndexPath) -> ReusableCellIdentifier
     func collectionSkeletonView(_ skeletonView: UICollectionView, supplementaryViewIdentifierOfKind: String, at indexPath: IndexPath) -> ReusableCellIdentifier?
+    func collectionSkeletonView(_ skeletonView: UICollectionView, skeletonCellForItemAt indexPath: IndexPath) -> UICollectionViewCell?
+    func collectionSkeletonView(_ skeletonView: UICollectionView, prepareCellForSkeleton cell: UICollectionViewCell, at indexPath: IndexPath)
 }
 
 public extension SkeletonCollectionViewDataSource {
     func collectionSkeletonView(_ skeletonView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
-        return SkeletonCollectionDataSource.automaticNumberOfRows
+        UICollectionView.automaticNumberOfSkeletonItems
     }
     
-    func collectionSkeletonView(_ skeletonView: UICollectionView,
-                                supplementaryViewIdentifierOfKind: String,
-                                at indexPath: IndexPath) -> ReusableCellIdentifier? {
-        return nil
+    func collectionSkeletonView(_ skeletonView: UICollectionView, supplementaryViewIdentifierOfKind: String, at indexPath: IndexPath) -> ReusableCellIdentifier? {
+        nil
     }
     
-    func numSections(in collectionSkeletonView: UICollectionView) -> Int { return 1 }
+    func numSections(in collectionSkeletonView: UICollectionView) -> Int {
+        1
+    }
+    
+    func collectionSkeletonView(_ skeletonView: UICollectionView, skeletonCellForItemAt indexPath: IndexPath) -> UICollectionViewCell? {
+        nil
+    }
+
+    func collectionSkeletonView(_ skeletonView: UICollectionView, prepareCellForSkeleton cell: UICollectionViewCell, at indexPath: IndexPath) { }
 }
 
 public protocol SkeletonCollectionViewDelegate: UICollectionViewDelegate { }

Sources/Collections/CollectionViews/UICollectionView+CollectionSkeleton.swift

@@ -9,6 +9,8 @@
 import UIKit
  
 extension UICollectionView: CollectionSkeleton {
+    public static let automaticNumberOfSkeletonItems = -1
+
     var estimatedNumberOfRows: Int {
         guard let flowlayout = collectionViewLayout as? UICollectionViewFlowLayout else { return 0 }
         switch flowlayout.scrollDirection {

Sources/Collections/SkeletonCollectionDataSource.swift

@@ -11,8 +11,6 @@ import UIKit
 public typealias ReusableCellIdentifier = String
 
 class SkeletonCollectionDataSource: NSObject {
-    static let automaticNumberOfRows = -1
-
     weak var originalTableViewDataSource: SkeletonTableViewDataSource?
     weak var originalCollectionViewDataSource: SkeletonCollectionViewDataSource?
     var rowHeight: CGFloat = 0.0
@@ -40,7 +38,7 @@ extension SkeletonCollectionDataSource: UITableViewDataSource {
 
         let numberOfRows = originalTableViewDataSource.collectionSkeletonView(tableView, numberOfRowsInSection: section)
 
-        if numberOfRows == Self.automaticNumberOfRows {
+        if numberOfRows == UITableView.automaticNumberOfSkeletonRows {
             return tableView.estimatedNumberOfRows
         } else {
             return numberOfRows
@@ -48,8 +46,17 @@ extension SkeletonCollectionDataSource: UITableViewDataSource {
     }
     
     func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
-        let cellIdentifier = originalTableViewDataSource?.collectionSkeletonView(tableView, cellIdentifierForRowAt: indexPath) ?? ""
-        let cell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier, for: indexPath)
+        guard let cell = originalTableViewDataSource?.collectionSkeletonView(tableView, skeletonCellForRowAt: indexPath) else {
+            let cellIdentifier = originalTableViewDataSource?.collectionSkeletonView(tableView, cellIdentifierForRowAt: indexPath) ?? ""
+            let fakeCell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier, for: indexPath)
+
+            originalTableViewDataSource?.collectionSkeletonView(tableView, prepareCellForSkeleton: fakeCell, at: indexPath)
+            skeletonViewIfContainerSkeletonIsActive(container: tableView, view: fakeCell)
+            
+            return fakeCell
+        }
+
+        originalTableViewDataSource?.collectionSkeletonView(tableView, prepareCellForSkeleton: cell, at: indexPath)
         skeletonViewIfContainerSkeletonIsActive(container: tableView, view: cell)
         return cell
     }
@@ -68,7 +75,7 @@ extension SkeletonCollectionDataSource: UICollectionViewDataSource {
 
         let numberOfItems = originalCollectionViewDataSource.collectionSkeletonView(collectionView, numberOfItemsInSection: section)
 
-        if numberOfItems == Self.automaticNumberOfRows {
+        if numberOfItems == UICollectionView.automaticNumberOfSkeletonItems {
             return collectionView.estimatedNumberOfRows
         } else {
             return numberOfItems
@@ -76,8 +83,17 @@ extension SkeletonCollectionDataSource: UICollectionViewDataSource {
     }
     
     func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
-        let cellIdentifier = originalCollectionViewDataSource?.collectionSkeletonView(collectionView, cellIdentifierForItemAt: indexPath) ?? ""
-        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellIdentifier, for: indexPath)
+        guard let cell = originalCollectionViewDataSource?.collectionSkeletonView(collectionView, skeletonCellForItemAt: indexPath) else {
+            let cellIdentifier = originalCollectionViewDataSource?.collectionSkeletonView(collectionView, cellIdentifierForItemAt: indexPath) ?? ""
+            let fakeCell = collectionView.dequeueReusableCell(withReuseIdentifier: cellIdentifier, for: indexPath)
+
+            originalCollectionViewDataSource?.collectionSkeletonView(collectionView, prepareCellForSkeleton: fakeCell, at: indexPath)
+            skeletonViewIfContainerSkeletonIsActive(container: collectionView, view: fakeCell)
+            
+            return fakeCell
+        }
+
+        originalCollectionViewDataSource?.collectionSkeletonView(collectionView, prepareCellForSkeleton: cell, at: indexPath)
         skeletonViewIfContainerSkeletonIsActive(container: collectionView, view: cell)
         return cell
     }

Sources/Collections/TableViews/SkeletonTableViewProtocols.swift

@@ -12,11 +12,13 @@ public protocol SkeletonTableViewDataSource: UITableViewDataSource {
     func numSections(in collectionSkeletonView: UITableView) -> Int
     func collectionSkeletonView(_ skeletonView: UITableView, numberOfRowsInSection section: Int) -> Int
     func collectionSkeletonView(_ skeletonView: UITableView, cellIdentifierForRowAt indexPath: IndexPath) -> ReusableCellIdentifier
+    func collectionSkeletonView(_ skeletonView: UITableView, skeletonCellForRowAt indexPath: IndexPath) -> UITableViewCell?
+    func collectionSkeletonView(_ skeletonView: UITableView, prepareCellForSkeleton cell: UITableViewCell, at indexPath: IndexPath)
 }
 
 public extension SkeletonTableViewDataSource {
     func collectionSkeletonView(_ skeletonView: UITableView, numberOfRowsInSection section: Int) -> Int {
-        return SkeletonCollectionDataSource.automaticNumberOfRows
+        return UITableView.automaticNumberOfSkeletonRows
     }
     
     func numSections(in collectionSkeletonView: UITableView) -> Int { return 1 }
@@ -27,6 +29,12 @@ public extension SkeletonTableViewDataSource {
     func collectionSkeletonView(_ skeletonView: UITableView, cellIdenfierForRowAt indexPath: IndexPath) -> ReusableCellIdentifier {
         return collectionSkeletonView(skeletonView, cellIdentifierForRowAt: indexPath)
     }
+    
+    func collectionSkeletonView(_ skeletonView: UITableView, skeletonCellForRowAt indexPath: IndexPath) -> UITableViewCell? {
+        nil
+    }
+
+    func collectionSkeletonView(_ skeletonView: UITableView, prepareCellForSkeleton cell: UITableViewCell, at indexPath: IndexPath) { }
 }
 
 public protocol SkeletonTableViewDelegate: UITableViewDelegate {

Sources/Collections/TableViews/UITableView+CollectionSkeleton.swift

@@ -11,6 +11,8 @@ import UIKit
 public typealias ReusableHeaderFooterIdentifier = String
 
 extension UITableView: CollectionSkeleton {
+    public static let automaticNumberOfSkeletonRows = -1
+
     var estimatedNumberOfRows: Int {
         return Int(ceil(frame.height / rowHeight))
     }

Sources/Extensions/UIView+Autolayout.swift

@@ -12,9 +12,17 @@ extension UIView {
         nonContentSizeLayoutConstraints.filter { $0.firstAttribute == NSLayoutConstraint.Attribute.height }
     }
     
+    var skeletonHeightConstraints: [NSLayoutConstraint] {
+        nonContentSizeLayoutConstraints.filter {
+            $0.firstAttribute == NSLayoutConstraint.Attribute.height
+                && $0.identifier?.contains("SkeletonView.Constraint.Height") ?? false
+        }
+    }
+    
     @discardableResult
     func setHeight(equalToConstant constant: CGFloat) -> NSLayoutConstraint {
         let heightConstraint = heightAnchor.constraint(equalToConstant: constant)
+        heightConstraint.identifier = "SkeletonView.Constraint.Height.\(constant)"
         NSLayoutConstraint.activate([heightConstraint])
         return heightConstraint
     }

Sources/Extensions/UIView+Extension.swift

@@ -14,9 +14,11 @@ enum ViewAssociatedKeys {
     static var labelViewState = "labelViewState"
     static var imageViewState = "imageViewState"
     static var buttonViewState = "buttonViewState"
+    static var headerFooterViewState = "headerFooterViewState"
     static var currentSkeletonConfig = "currentSkeletonConfig"
     static var skeletonCornerRadius = "skeletonCornerRadius"
     static var disabledWhenSkeletonIsActive = "disabledWhenSkeletonIsActive"
+    static var delayedShowSkeletonWorkItem = "delayedShowSkeletonWorkItem"
 }
 // codebeat:enable[TOO_MANY_IVARS]
 
@@ -54,4 +56,9 @@ extension UIView {
     var isSuperviewAStackView: Bool {
         superview is UIStackView
     }
+    
+    var delayedShowSkeletonWorkItem: DispatchWorkItem? {
+        get { return ao_get(pkey: &ViewAssociatedKeys.delayedShowSkeletonWorkItem) as? DispatchWorkItem }
+        set { ao_setOptional(newValue, pkey: &ViewAssociatedKeys.delayedShowSkeletonWorkItem) }
+    }
 }

Sources/Helpers/PrepareForSkeletonProtocol.swift

@@ -22,7 +22,6 @@ extension UIView {
 
 extension UILabel {
     var desiredHeightBasedOnNumberOfLines: CGFloat {
-        let lineHeight = constraintHeight ?? SkeletonAppearance.default.multilineHeight
         let spaceNeededForEachLine = lineHeight * CGFloat(numberOfLines)
         let spaceNeededForSpaces = skeletonLineSpacing * CGFloat(numberOfLines - 1)
         let padding = paddingInsets.top + paddingInsets.bottom
@@ -47,10 +46,7 @@ extension UILabel {
         }
     }
     
-    func restoreBackupHeightConstraints() {
-        heightConstraints.forEach {
-            removeConstraint($0)
-        }
+    func restoreBackupHeightConstraintsIfNeeded() {
         guard !backupHeightConstraints.isEmpty else { return }
         NSLayoutConstraint.activate(backupHeightConstraints)
         backupHeightConstraints.removeAll()
@@ -125,3 +121,13 @@ extension UIButton {
         }
     }
 }
+
+extension UITableViewHeaderFooterView {
+    override func prepareViewForSkeleton() {
+        backgroundView?.backgroundColor = .clear
+        
+        if isUserInteractionDisabledWhenSkeletonIsActive {
+            isUserInteractionEnabled = false
+        }
+    }
+}

Sources/Multilines/ContainsMultilineText.swift

@@ -11,8 +11,8 @@ enum MultilineAssociatedKeys {
 }
 
 protocol ContainsMultilineText {
-    var constraintHeight: CGFloat? { get }
-    var numLines: Int { get }
+    var lineHeight: CGFloat { get }
+    var numberOfLines: Int { get }
     var lastLineFillingPercent: Int { get }
     var multilineCornerRadius: Int { get }
     var multilineSpacing: CGFloat { get }

Sources/Multilines/UILabel+Multiline.swift

@@ -27,15 +27,11 @@ public extension UILabel {
     }
 }
 
-extension UILabel: ContainsMultilineText {
-    var constraintHeight: CGFloat? {
-        backupHeightConstraints.first?.constant
+extension UILabel: ContainsMultilineText {    
+    var lineHeight: CGFloat {
+        backupHeightConstraints.first?.constant ?? SkeletonAppearance.default.multilineHeight
     }
-
-    var numLines: Int {
-        return numberOfLines
-    }
-
+    
     var lastLineFillingPercent: Int {
         get { return ao_get(pkey: &MultilineAssociatedKeys.lastLineFillingPercent) as? Int ?? SkeletonAppearance.default.multilineLastLineFillPercent }
         set { ao_set(newValue, pkey: &MultilineAssociatedKeys.lastLineFillingPercent) }

Sources/Multilines/UITextView+Multiline.swift

@@ -28,11 +28,19 @@ public extension UITextView {
 }
 
 extension UITextView: ContainsMultilineText {
-    var constraintHeight: CGFloat? {
-        heightConstraints.first?.constant
+    var lineHeight: CGFloat {
+        if let fontLineHeight = font?.lineHeight {
+            if let heightConstraints = heightConstraints.first?.constant {
+                return (fontLineHeight > heightConstraints) ? heightConstraints : fontLineHeight
+            }
+            
+            return fontLineHeight
+        }
+        
+        return SkeletonAppearance.default.multilineHeight
     }
     
-    var numLines: Int {
+    var numberOfLines: Int {
         -1
     }
 	

Sources/Recoverable/Recoverable.swift

@@ -57,12 +57,16 @@ extension UILabel {
     override func recoverViewState(forced: Bool) {
         super.recoverViewState(forced: forced)
         startTransition { [weak self] in
-            guard let storedLabelState = self?.labelState else { return }
+            guard let self = self,
+                  let storedLabelState = self.labelState else {
+                return
+            }
             
-            self?.restoreBackupHeightConstraints()
+            NSLayoutConstraint.deactivate(self.skeletonHeightConstraints)
+            self.restoreBackupHeightConstraintsIfNeeded()
             
-            if self?.textColor == .clear || forced {
-                self?.textColor = storedLabelState.textColor
+            if self.textColor == .clear || forced {
+                self.textColor = storedLabelState.textColor
             }
         }
     }
@@ -157,3 +161,22 @@ extension UIButton {
         }
     }
 }
+
+extension UITableViewHeaderFooterView {
+    var headerFooterState: RecoverableTableViewHeaderFooterViewState? {
+        get { return ao_get(pkey: &ViewAssociatedKeys.headerFooterViewState) as? RecoverableTableViewHeaderFooterViewState }
+        set { ao_setOptional(newValue, pkey: &ViewAssociatedKeys.headerFooterViewState) }
+    }
+    
+    override func saveViewState() {
+        super.saveViewState()
+        headerFooterState = RecoverableTableViewHeaderFooterViewState(view: self)
+    }
+    
+    override func recoverViewState(forced: Bool) {
+        super.recoverViewState(forced: forced)
+        startTransition { [weak self] in
+            self?.backgroundView?.backgroundColor = self?.headerFooterState?.backgroundViewColor
+        }
+    }
+}

Sources/Recoverable/RecoverableViewState.swift

@@ -59,3 +59,11 @@ struct RecoverableButtonViewState {
         self.title = view.titleLabel?.text
     }
 }
+
+struct RecoverableTableViewHeaderFooterViewState {
+    var backgroundViewColor: UIColor?
+    
+    init(view: UITableViewHeaderFooterView) {
+        self.backgroundViewColor = view.backgroundView?.backgroundColor
+    }
+}

Sources/SkeletonLayer.swift

@@ -83,9 +83,8 @@ struct SkeletonLayer {
     /// If there is more than one line, or custom preferences have been set for a single line, draw custom layers
     func addTextLinesIfNeeded() {
         guard let textView = holderAsTextView else { return }
-        let lineHeight = textView.constraintHeight ?? SkeletonAppearance.default.multilineHeight
-        let config = SkeletonMultilinesLayerConfig(lines: textView.numLines,
-                                                   lineHeight: lineHeight,
+        let config = SkeletonMultilinesLayerConfig(lines: textView.numberOfLines,
+                                                   lineHeight: textView.lineHeight,
                                                    type: type,
                                                    lastLineFillPercent: textView.lastLineFillingPercent,
                                                    multilineCornerRadius: textView.multilineCornerRadius,
@@ -98,9 +97,8 @@ struct SkeletonLayer {
     
     func updateLinesIfNeeded() {
         guard let textView = holderAsTextView else { return }
-        let lineHeight = textView.constraintHeight ?? SkeletonAppearance.default.multilineHeight
-        let config = SkeletonMultilinesLayerConfig(lines: textView.numLines,
-                                                   lineHeight: lineHeight,
+        let config = SkeletonMultilinesLayerConfig(lines: textView.numberOfLines,
+                                                   lineHeight: textView.lineHeight,
                                                    type: type,
                                                    lastLineFillPercent: textView.lastLineFillingPercent,
                                                    multilineCornerRadius: textView.multilineCornerRadius,
@@ -113,7 +111,7 @@ struct SkeletonLayer {
     
     var holderAsTextView: ContainsMultilineText? {
         guard let textView = holder as? ContainsMultilineText,
-            (textView.numLines == -1 || textView.numLines == 0 || textView.numLines > 1 || textView.numLines == 1 && !SkeletonAppearance.default.renderSingleLineAsView) else {
+            (textView.numberOfLines == -1 || textView.numberOfLines == 0 || textView.numberOfLines > 1 || textView.numberOfLines == 1 && !SkeletonAppearance.default.renderSingleLineAsView) else {
                 return nil
         }
         return textView

Sources/SkeletonView.swift

@@ -9,20 +9,63 @@ public extension UIView {
     ///   - color: The color of the skeleton. Defaults to `SkeletonAppearance.default.tintColor`.
     ///   - transition: The style of the transition when the skeleton appears. Defaults to `.crossDissolve(0.25)`.
     func showSkeleton(usingColor color: UIColor = SkeletonAppearance.default.tintColor, transition: SkeletonTransitionStyle = .crossDissolve(0.25)) {
+        delayedShowSkeletonWorkItem?.cancel()
         let config = SkeletonConfig(type: .solid, colors: [color], transition: transition)
         showSkeleton(skeletonConfig: config)
     }
     
+    /// Shows the skeleton using the view that calls this method as root view.
+    ///
+    /// - Parameters:
+    ///   - color: The color of the skeleton. Defaults to `SkeletonAppearance.default.tintColor`.
+    ///   - animated: If the skeleton is animated or not. Defaults to `true`.
+    ///   - delay: The amount of time (measured in seconds) to wait before show the skeleton.
+    ///   - transition: The style of the transition when the skeleton appears. Defaults to `.crossDissolve(0.25)`.
+    func showSkeleton(usingColor color: UIColor = SkeletonAppearance.default.tintColor, animated: Bool = true, delay: TimeInterval, transition: SkeletonTransitionStyle = .crossDissolve(0.25)) {
+        delayedShowSkeletonWorkItem?.cancel()
+        
+        delayedShowSkeletonWorkItem = DispatchWorkItem { [weak self] in
+            let config = SkeletonConfig(type: .solid, colors: [color], animated: animated, transition: transition)
+            self?.showSkeleton(skeletonConfig: config)
+        }
+        
+        DispatchQueue.main.asyncAfter(deadline: .now() + delay, execute: delayedShowSkeletonWorkItem!)
+    }
+    
     /// Shows the gradient skeleton without animation using the view that calls this method as root view.
     ///
     /// - Parameters:
     ///   - gradient: The gradient of the skeleton. Defaults to `SkeletonAppearance.default.gradient`.
     ///   - transition: The style of the transition when the skeleton appears. Defaults to `.crossDissolve(0.25)`.
     func showGradientSkeleton(usingGradient gradient: SkeletonGradient = SkeletonAppearance.default.gradient, transition: SkeletonTransitionStyle = .crossDissolve(0.25)) {
+        delayedShowSkeletonWorkItem?.cancel()
         let config = SkeletonConfig(type: .gradient, colors: gradient.colors, transition: transition)
         showSkeleton(skeletonConfig: config)
     }
     
+    /// Shows the gradient skeleton using the view that calls this method as root view.
+    ///
+    /// - Parameters:
+    ///   - gradient: The gradient of the skeleton. Defaults to `SkeletonAppearance.default.gradient`.
+    ///   - animated: If the skeleton is animated or not. Defaults to `true`.
+    ///   - delay: The amount of time (measured in seconds) to wait before show the skeleton.
+    ///   - transition: The style of the transition when the skeleton appears. Defaults to `.crossDissolve(0.25)`.
+    func showGradientSkeleton(
+        usingGradient gradient: SkeletonGradient = SkeletonAppearance.default.gradient,
+        animated: Bool = true,
+        delay: TimeInterval,
+        transition: SkeletonTransitionStyle = .crossDissolve(0.25)
+    ) {
+        delayedShowSkeletonWorkItem?.cancel()
+        
+        delayedShowSkeletonWorkItem = DispatchWorkItem { [weak self] in
+            let config = SkeletonConfig(type: .gradient, colors: gradient.colors, animated: animated, transition: transition)
+            self?.showSkeleton(skeletonConfig: config)
+        }
+        
+        DispatchQueue.main.asyncAfter(deadline: .now() + delay, execute: delayedShowSkeletonWorkItem!)
+    }
+    
     /// Shows the animated skeleton using the view that calls this method as root view.
     ///
     /// If animation is nil, sliding animation will be used, with direction left to right.
@@ -32,6 +75,7 @@ public extension UIView {
     ///   - animation: The animation of the skeleton. Defaults to `nil`.
     ///   - transition: The style of the transition when the skeleton appears. Defaults to `.crossDissolve(0.25)`.
     func showAnimatedSkeleton(usingColor color: UIColor = SkeletonAppearance.default.tintColor, animation: SkeletonLayerAnimation? = nil, transition: SkeletonTransitionStyle = .crossDissolve(0.25)) {
+        delayedShowSkeletonWorkItem?.cancel()
         let config = SkeletonConfig(type: .solid, colors: [color], animated: true, animation: animation, transition: transition)
         showSkeleton(skeletonConfig: config)
     }
@@ -45,6 +89,7 @@ public extension UIView {
     ///   - animation: The animation of the skeleton. Defaults to `nil`.
     ///   - transition: The style of the transition when the skeleton appears. Defaults to `.crossDissolve(0.25)`.
     func showAnimatedGradientSkeleton(usingGradient gradient: SkeletonGradient = SkeletonAppearance.default.gradient, animation: SkeletonLayerAnimation? = nil, transition: SkeletonTransitionStyle = .crossDissolve(0.25)) {
+        delayedShowSkeletonWorkItem?.cancel()
         let config = SkeletonConfig(type: .gradient, colors: gradient.colors, animated: true, animation: animation, transition: transition)
         showSkeleton(skeletonConfig: config)
     }
@@ -75,6 +120,7 @@ public extension UIView {
     }
     
     func hideSkeleton(reloadDataAfter reload: Bool = true, transition: SkeletonTransitionStyle = .crossDissolve(0.25)) {
+        delayedShowSkeletonWorkItem?.cancel()
         flowDelegate?.willBeginHidingSkeletons(rootView: self)
         recursiveHideSkeleton(reloadDataAfter: reload, transition: transition, root: self)
     }
@@ -277,14 +323,22 @@ extension UIView {
             .setHolder(self)
             .build()
             else { return }
-
+        
         self.skeletonLayer = skeletonLayer
-        layer.insertSublayer(skeletonLayer,
-                             at: UInt32.max,
-                             transition: config.transition) { [weak self] in
-                                if config.animated {
-                                    self?.startSkeletonAnimation(config.animation)
-                                }
+        layer.insertSkeletonLayer(
+            skeletonLayer,
+            atIndex: UInt32.max,
+            transition: config.transition
+        ) { [weak self] in
+            guard let self = self else { return }
+            
+            /// Workaround to fix the problem when inserting a sublayer and
+            /// the content offset is modified by the system.
+            (self as? UITextView)?.setContentOffset(.zero, animated: false)
+            
+            if config.animated {
+                self.startSkeletonAnimation(config.animation)
+            }
         }
         status = .on
     }

Sources/Transitions/UIView+Transitions.swift

@@ -3,13 +3,13 @@
 import UIKit
 
 extension CALayer {
-    func insertSublayer(_ layer: SkeletonLayer, at idx: UInt32, transition: SkeletonTransitionStyle, completion: (() -> Void)? = nil) {
-        insertSublayer(layer.contentLayer, at: idx)
+    func insertSkeletonLayer(_ sublayer: SkeletonLayer, atIndex index: UInt32, transition: SkeletonTransitionStyle, completion: (() -> Void)? = nil) {
+        insertSublayer(sublayer.contentLayer, at: index)
         switch transition {
         case .none:
             completion?()
         case .crossDissolve(let duration):
-			layer.contentLayer.setOpacity(from: 0, to: 1, duration: duration, completion: completion)
+            sublayer.contentLayer.setOpacity(from: 0, to: 1, duration: duration, completion: completion)
         }
     }
 }