Delay the presentation of the skeletons (#411)

README.md

@@ -504,6 +504,24 @@ By default, the user interaction is disabled for skeletonized items, but if you
 view.isUserInteractionDisabledWhenSkeletonIsActive = false  // The view will be active when the skeleton will be active.
 ```
 
+**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.
+
+```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.

SkeletonView.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name         = "SkeletonView"
-  s.version      = "1.17.1"
+  s.version      = "1.17.2"
   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/Extensions/UIView+Extension.swift

@@ -17,6 +17,7 @@ enum ViewAssociatedKeys {
     static var currentSkeletonConfig = "currentSkeletonConfig"
     static var skeletonCornerRadius = "skeletonCornerRadius"
     static var disabledWhenSkeletonIsActive = "disabledWhenSkeletonIsActive"
+    static var delayedShowSkeletonWorkItem = "delayedShowSkeletonWorkItem"
 }
 // codebeat:enable[TOO_MANY_IVARS]
 
@@ -54,4 +55,9 @@ 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

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/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)
         }
     }
 }