Add prepareCellForSkeleton for UITableView and UICollectionView (#415)

* 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>

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
@@ -194,17 +191,30 @@ func collectionSkeletonView(_ skeletonView: UITableView, numberOfRowsInSection s
 > 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)
 }
 ```
 
@@ -506,7 +518,7 @@ view.isUserInteractionDisabledWhenSkeletonIsActive = false  // The view will be
 
 **Delayed show skeleton**
 
-You can delay the showIf the views are updated quickly you canAn optional delay applied to the transition, like the transition duration.
+You can delay the presentation of the skeleton if the views update quickly.
 
 ```swift
 func showSkeleton(usingColor: UIColor,

SkeletonView.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name         = "SkeletonView"
-  s.version      = "1.17.2"
+  s.version      = "1.18.0"
   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 UICollectionView.automaticNumberOfSkeletonItems
+        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/SkeletonCollectionDataSource.swift

@@ -46,8 +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
     }
@@ -74,8 +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

@@ -12,6 +12,8 @@ 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 {
@@ -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 {