Support alpha threshold

ImpressionKit/ImpressionGroup.swift

@@ -16,8 +16,11 @@ public class ImpressionGroup<IndexType: Hashable> {
     // Chage the threshold of duration in screen (in seconds). The view will be impressed if it keeps being in screen after this seconds. Apply to the group. `UIView.durationThreshold` will be used if it's nil.
     public var durationThreshold: Float?
 
-    // Chage the threshold of area ratio in screen. It's from 0 to 1. The view will be impressed if it's area ratio keeps being bigger than this value. Apply to the group. `UIView.areaRatioThreshold` will be used if it's nil.
+    // Chage the threshold of area ratio in screen. It's from 0 to 1. The view will be impressed if it's area ratio remains equal to or greater than this value. Apply to the group. `UIView.areaRatioThreshold` will be used if it's nil.
     public var areaRatioThreshold: Float?
+
+    // Chage the threshold of alpha. It's from 0 to 1. The view will be impressed if it's alpha is equal to or greater than this value. Apply to the group. `UIView.alphaThreshold` will be used if it's nil.
+    public var alphaThreshold: Float?
 
     // Retrigger the impression. Apply to the group. `UIView.redetectOptions` will be used if it's nil.
     public var redetectOptions: UIView.Redetect? {
@@ -69,7 +72,17 @@ public class ImpressionGroup<IndexType: Hashable> {
         self.changeState(index: index, view: view, state: state)
     }
 
-    public init(impressionGroupCallback: @escaping ImpressionGroupCallback) {
+    public init(detectionInterval: Float? = nil,
+         durationThreshold: Float? = nil,
+         areaRatioThreshold: Float? = nil,
+         alphaThreshold: Float? = nil,
+         redetectOptions: UIView.Redetect? = nil,
+         impressionGroupCallback: @escaping ImpressionGroupCallback) {
+        self.detectionInterval = detectionInterval
+        self.durationThreshold = durationThreshold
+        self.areaRatioThreshold = areaRatioThreshold
+        self.alphaThreshold = alphaThreshold
+        self.redetectOptions = redetectOptions
         self.impressionGroupCallback = impressionGroupCallback
         readdNotificationObserver()
     }
@@ -103,6 +116,7 @@ public class ImpressionGroup<IndexType: Hashable> {
         view.detectionInterval = self.detectionInterval
         view.durationThreshold = self.durationThreshold
         view.areaRatioThreshold = self.areaRatioThreshold
+        view.alphaThreshold = self.alphaThreshold
         // No need to set .willResignActive and .didEnterBackground for views. Group will handle this.
         var redetectOptions = self.redetectOptions
         redetectOptions?.remove(.willResignActive)

ImpressionKit/UIViewFunctionExtension.swift

@@ -207,7 +207,8 @@ extension UIView {
     // MARK: - Algorithm
 
     private func areaRatio() -> Float {
-        guard self.isHidden == false && self.alpha > 0 else {
+        let alphaThreshold = CGFloat(self.alphaThreshold ?? UIView.alphaThreshold)
+        guard self.isHidden == false && self.alpha >= alphaThreshold else {
             return 0
         }
         if let window = self as? UIWindow,
@@ -219,14 +220,14 @@ extension UIView {
         } else {
             // It's normal view
             guard let window = self.window,
-                  window.isHidden == false && window.alpha > 0 else {
+                  window.isHidden == false && window.alpha >= alphaThreshold else {
                 return 0
             }
-            // If super view hidden or alpha <= 0, self can't show
+            // If super view hidden or alpha < alphaThreshold, self can't show
             var aView = self
             var frameInSuperView = self.bounds
             while let superView = aView.superview {
-                guard superView.isHidden == false && superView.alpha > 0 else {
+                guard superView.isHidden == false && superView.alpha >= alphaThreshold else {
                     return 0
                 }
                 frameInSuperView = aView.convert(frameInSuperView, to: superView)

ImpressionKit/UIViewPropertyExtension.swift

@@ -16,6 +16,7 @@ private var stateKey = 0
 private var detectionIntervalKey = 0
 private var durationThresholdKey = 0
 private var areaRatioThresholdKey = 0
+private var alphaThresholdKey = 0
 private var redetectOptionsKey = 0
 private var hookingDeallocTokenKey = 0
 private var hookingDidMoveToWindowTokenKey = 0
@@ -95,10 +96,10 @@ extension UIView {
         }
     }
 
-    // Chage the threshold of area ratio in screen. It's from 0 to 1. The view will be impressed if it's area ratio keeps being bigger than this value. Apply to all views
+    // Chage the threshold of area ratio in screen. It's from 0 to 1. The view will be impressed if it's area ratio remains equal to or greater than this value. Apply to all views
     public static var areaRatioThreshold: Float = 0.5
 
-    // Chage the threshold of area ratio in screen. It's from 0 to 1. The view will be impressed if it's area ratio keeps being bigger than this value. Apply to the specific view. `UIView.areaRatioThreshold` will be used if it's nil.
+    // Chage the threshold of area ratio in screen. It's from 0 to 1. The view will be impressed if it's area ratio remains equal to or greater than this value. Apply to the specific view. `UIView.areaRatioThreshold` will be used if it's nil.
     public var areaRatioThreshold: Float? {
         set {
             objc_setAssociatedObject(self, &areaRatioThresholdKey, newValue, .OBJC_ASSOCIATION_COPY_NONATOMIC)
@@ -109,17 +110,31 @@ extension UIView {
         }
     }
 
+    // Chage the threshold of alpha. It's from 0 to 1. The view will be impressed if it's alpha is equal to or greater than this value. Apply to all views
+    public static var alphaThreshold: Float = 0.1
+
+    // Chage the threshold of alpha. It's from 0 to 1. The view will be impressed if it's alpha is equal to or greater than this value. Apply to the specific view. `UIView.alphaThreshold` will be used if it's nil.
+    public var alphaThreshold: Float? {
+        set {
+            objc_setAssociatedObject(self, &alphaThresholdKey, newValue, .OBJC_ASSOCIATION_COPY_NONATOMIC)
+        }
+
+        get {
+            return objc_getAssociatedObject(self, &alphaThresholdKey) as? Float
+        }
+    }
+
     public struct Redetect: OptionSet {
 
         public let rawValue: Int
         public init(rawValue: Int) {
             self.rawValue = rawValue
         }
 
-        // Retrigger the impression event when a view has left from the screen (The UIViewController (page) is still here, Just the view is out of the screen).
+        // Retrigger the impression event when a view left from the screen (The UIViewController (page) is still here, Just the view is out of the screen).
         public static let leftScreen = Redetect(rawValue: 1 << 0)
 
-        // Retrigger the impression event when the UIViewController which the view in did disappear.
+        // Retrigger the impression event when the UIViewController of the view disappear.
         public static let viewControllerDidDisappear = Redetect(rawValue: 1 << 1)
 
         // Retrigger the impression event when the App did enter background.
@@ -147,37 +162,43 @@ extension UIView {
 
     var hookingDeallocToken: Token? {
         set {
-            objc_setAssociatedObject(self, &hookingDeallocTokenKey, newValue, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
+            let closure = { return newValue }
+            objc_setAssociatedObject(self, &hookingDeallocTokenKey, closure, .OBJC_ASSOCIATION_COPY_NONATOMIC)
         }
 
         get {
-            return objc_getAssociatedObject(self, &hookingDeallocTokenKey) as? Token
+            guard let closure = objc_getAssociatedObject(self, &hookingDeallocTokenKey) as? () -> Token? else { return nil }
+            return closure()
         }
     }
 
     var hookingDidMoveToWindowToken: Token? {
         set {
-            objc_setAssociatedObject(self, &hookingDidMoveToWindowTokenKey, newValue, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
+            let closure = { return newValue }
+            objc_setAssociatedObject(self, &hookingDidMoveToWindowTokenKey, closure, .OBJC_ASSOCIATION_COPY_NONATOMIC)
         }
 
         get {
-            return objc_getAssociatedObject(self, &hookingDidMoveToWindowTokenKey) as? Token
+            guard let closure = objc_getAssociatedObject(self, &hookingDidMoveToWindowTokenKey) as? () -> Token? else { return nil }
+            return closure()
         }
     }
 
     var hookingViewDidDisappearToken: Token? {
         set {
-            objc_setAssociatedObject(self, &hookingViewDidDisappearTokenKey, newValue, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
+            let closure = { return newValue }
+            objc_setAssociatedObject(self, &hookingViewDidDisappearTokenKey, closure, .OBJC_ASSOCIATION_COPY_NONATOMIC)
         }
 
         get {
-            return objc_getAssociatedObject(self, &hookingViewDidDisappearTokenKey) as? Token
+            guard let closure = objc_getAssociatedObject(self, &hookingViewDidDisappearTokenKey) as? () -> Token? else { return nil }
+            return closure()
         }
     }
 
     var notificationTokens: [NSObjectProtocol] {
         set {
-            objc_setAssociatedObject(self, &notificationTokensKey, newValue, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
+            objc_setAssociatedObject(self, &notificationTokensKey, newValue, .OBJC_ASSOCIATION_COPY_NONATOMIC)
         }
 
         get {

ImpressionKitExample/ImpressionKitExample/AppDelegate.swift

@@ -19,6 +19,7 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
         UIView.detectionInterval = HomeViewController.detectionInterval
         UIView.durationThreshold = HomeViewController.durationThreshold
         UIView.areaRatioThreshold = HomeViewController.areaRatioThreshold
+        UIView.alphaThreshold = HomeViewController.alphaThreshold
         UIView.redetectOptions = HomeViewController.redetectOptions
         ImpressionKitDebug.shared.openLogs()
 

ImpressionKitExample/ImpressionKitExample/CollectionViewDemo2ViewController.swift

@@ -27,7 +27,7 @@ class CollectionViewDemo2ViewController: UIViewController, UICollectionViewDataS
         if state.isImpressed {
             print("impressed index: \(index.section), \(index.row)")
         }
-        if let cell = view as? Cell {
+        if let cell = view.superview as? Cell {
             cell.updateUI(state: state)
         }
     }
@@ -87,7 +87,8 @@ class CollectionViewDemo2ViewController: UIViewController, UICollectionViewDataS
 
     func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
         let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! Cell
-        self.group.bind(view: cell, index: indexPath, ignoreDetection: indexPath.section != 1)
+        cell.contentView.alpha = CGFloat(HomeViewController.alphaInDemo)
+        self.group.bind(view: cell.contentView, index: indexPath, ignoreDetection: indexPath.section != 1)
         cell.index = indexPath.row
         cell.updateUI(state: self.group.states[indexPath])
         return cell
@@ -136,7 +137,7 @@ private class Cell: UICollectionViewCell {
             self.contentView.backgroundColor = .green
         case .inScreen(_):
             self.contentView.backgroundColor = .white
-            UIView.animate(withDuration: TimeInterval(self.durationThreshold ?? UIView.durationThreshold), delay: 0, options: [.curveLinear, .allowUserInteraction], animations: {
+            UIView.animate(withDuration: TimeInterval(self.contentView.durationThreshold ?? UIView.durationThreshold), delay: 0, options: [.curveLinear, .allowUserInteraction], animations: {
                 self.contentView.backgroundColor = .red
             }, completion: nil)
         default:

ImpressionKitExample/ImpressionKitExample/CollectionViewDemoViewController.swift

@@ -27,7 +27,7 @@ class CollectionViewDemoViewController: UIViewController, UICollectionViewDataSo
         if state.isImpressed {
             print("impressed index: \(index.row)")
         }
-        if let cell = view as? Cell {
+        if let cell = view.superview as? Cell {
             cell.updateUI(state: state)
         }
     }
@@ -83,7 +83,8 @@ class CollectionViewDemoViewController: UIViewController, UICollectionViewDataSo
 
     func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
         let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! Cell
-        self.group.bind(view: cell, index: indexPath)
+        cell.contentView.alpha = CGFloat(HomeViewController.alphaInDemo)
+        self.group.bind(view: cell.contentView, index: indexPath)
         cell.index = indexPath.row
         cell.updateUI(state: self.group.states[indexPath])
         return cell
@@ -132,7 +133,7 @@ private class Cell: UICollectionViewCell {
             self.contentView.backgroundColor = .green
         case .inScreen(_):
             self.contentView.backgroundColor = .white
-            UIView.animate(withDuration: TimeInterval(self.durationThreshold ?? UIView.durationThreshold), delay: 0, options: [.curveLinear, .allowUserInteraction], animations: {
+            UIView.animate(withDuration: TimeInterval(self.contentView.durationThreshold ?? UIView.durationThreshold), delay: 0, options: [.curveLinear, .allowUserInteraction], animations: {
                 self.contentView.backgroundColor = .red
             }, completion: nil)
         default:

ImpressionKitExample/ImpressionKitExample/HomeViewController.swift

@@ -14,6 +14,8 @@ class HomeViewController: FormViewController {
     private static let detectionIntervalKey = "detectionIntervalKey"
     private static let durationThresholdKey = "durationThresholdKey"
     private static let areaRatioThresholdKey = "areaRatioThresholdKey"
+    private static let alphaThresholdKey = "alphaThresholdKey"
+    private static let alphaInDemoKey = "alphaInDemoKey"
     private static let redetectOptionsKey = "redetectOptionsKey"
 
     static var detectionInterval: Float {
@@ -53,6 +55,29 @@ class HomeViewController: FormViewController {
             UserDefaults.standard.set(newValue, forKey: areaRatioThresholdKey)
         }
     }
+    static var alphaThreshold: Float {
+        get {
+            guard UserDefaults.standard.object(forKey: alphaThresholdKey) != nil else {
+                return UIView.alphaThreshold
+            }
+            return UserDefaults.standard.float(forKey: alphaThresholdKey)
+        }
+        set {
+            UIView.alphaThreshold = newValue
+            UserDefaults.standard.set(newValue, forKey: alphaThresholdKey)
+        }
+    }
+    static var alphaInDemo: Float {
+        get {
+            guard UserDefaults.standard.object(forKey: alphaInDemoKey) != nil else {
+                return 1
+            }
+            return UserDefaults.standard.float(forKey: alphaInDemoKey)
+        }
+        set {
+            UserDefaults.standard.set(newValue, forKey: alphaInDemoKey)
+        }
+    }
     static var redetectOptions: UIView.Redetect {
         get {
             guard UserDefaults.standard.object(forKey: redetectOptionsKey) != nil else {
@@ -156,6 +181,28 @@ class HomeViewController: FormViewController {
         }.onChange({ (row) in
             HomeViewController.areaRatioThreshold = Float((row.value ?? 0) / 100)
         })
+        <<< SliderRow() {
+            $0.title = "Alpha Threshold"
+            $0.value = Float(Int(HomeViewController.alphaThreshold * 100))
+            $0.cell.slider.minimumValue = 1
+            $0.cell.slider.maximumValue = 100
+            $0.displayValueFor = {
+                return "\(Int($0 ?? 0))%"
+            }
+        }.onChange({ (row) in
+            HomeViewController.alphaThreshold = Float((row.value ?? 0) / 100)
+        })
+        <<< SliderRow() {
+            $0.title = "Alpha of views in Demo"
+            $0.value = Float(Int(HomeViewController.alphaInDemo * 100))
+            $0.cell.slider.minimumValue = 1
+            $0.cell.slider.maximumValue = 100
+            $0.displayValueFor = {
+                return "\(Int($0 ?? 0))%"
+            }
+        }.onChange({ (row) in
+            HomeViewController.alphaInDemo = Float((row.value ?? 0) / 100)
+        })
         <<< SwitchRow() {
             $0.title = "Redetect When Left Screen"
             $0.value = HomeViewController.redetectOptions.contains(.leftScreen)
@@ -203,6 +250,8 @@ class HomeViewController: FormViewController {
             HomeViewController.detectionInterval = 0.2
             HomeViewController.durationThreshold = 1
             HomeViewController.areaRatioThreshold = 0.5
+            HomeViewController.alphaThreshold = 0.1
+            HomeViewController.alphaInDemo = 1
             HomeViewController.redetectOptions = []
             self?.setUpForm()
         }

ImpressionKitExample/ImpressionKitExample/ScrollViewDemoViewController.swift

@@ -96,6 +96,7 @@ private class CellView: UIView {
         super.init(frame: CGRect.zero)
         self.layer.borderColor = UIColor.gray.cgColor
         self.layer.borderWidth = 0.5
+        self.alpha = CGFloat(HomeViewController.alphaInDemo)
 
         self.label.frame = self.bounds
         self.addSubview(self.label)

ImpressionKitExample/ImpressionKitExample/TableViewDemoViewController.swift

@@ -21,7 +21,7 @@ class TableViewDemoViewController: UIViewController, UITableViewDataSource, UITa
         if state.isImpressed {
             print("impressed index: \(index.row)")
         }
-        if let cell = view as? Cell {
+        if let cell = view.superview as? Cell {
             cell.updateUI(state: state)
         }
     }
@@ -76,7 +76,8 @@ class TableViewDemoViewController: UIViewController, UITableViewDataSource, UITa
 
     func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
         let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! Cell
-        self.group.bind(view: cell, index: indexPath)
+        cell.contentView.alpha = CGFloat(HomeViewController.alphaInDemo)
+        self.group.bind(view: cell.contentView, index: indexPath)
         cell.index = indexPath.row
         cell.updateUI(state: self.group.states[indexPath])
         return cell
@@ -125,7 +126,7 @@ private class Cell: UITableViewCell {
             self.contentView.backgroundColor = .green
         case .inScreen(_):
             self.contentView.backgroundColor = .white
-            UIView.animate(withDuration: TimeInterval(self.durationThreshold ?? UIView.durationThreshold), delay: 0, options: [.curveLinear, .allowUserInteraction], animations: {
+            UIView.animate(withDuration: TimeInterval(self.contentView.durationThreshold ?? UIView.durationThreshold), delay: 0, options: [.curveLinear, .allowUserInteraction], animations: {
                 self.contentView.backgroundColor = .red
             }, completion: nil)
         default: