Fix iOS 13 compatibility

dreampiggy · dreampiggy · commit e1c32aea7d21 · 2022-09-21T20:14:30.000+08:00
Revert back the onPlatformAppear to fix iOS 14+ behavior
Use backport for all OSs
diff --git a/SDWebImageSwiftUI/Classes/AnimatedImage.swift b/SDWebImageSwiftUI/Classes/AnimatedImage.swift
@@ -101,15 +101,7 @@ final class AnimatedImageConfiguration: ObservableObject {
 /// A Image View type to load image from url, data or bundle. Supports animated and static image format.
 @available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
 public struct AnimatedImage : PlatformViewRepresentable {
-    @SwiftUI.StateObject var imageModel_SwiftUI = AnimatedImageModel()
-    @Backport.StateObject var imageModel_Backport = AnimatedImageModel()
-    var imageModel: AnimatedImageModel {
-        if #available(iOS 14.0, macOS 11.0, tvOS 14.0, watchOS 7.0, *) {
-            return imageModel_SwiftUI
-        } else {
-            return imageModel_Backport
-        }
-    }
+    @ObservedObject var imageModel: AnimatedImageModel
     @ObservedObject var imageHandler = AnimatedImageHandler()
     @ObservedObject var imageLayout = AnimatedImageLayout()
     @ObservedObject var imageConfiguration = AnimatedImageConfiguration()
@@ -186,11 +178,7 @@ public struct AnimatedImage : PlatformViewRepresentable {
     
     init(imageModel: AnimatedImageModel, isAnimating: Binding<Bool>) {
         self._isAnimating = isAnimating
-        if #available(iOS 14.0, macOS 11.0, tvOS 14.0, watchOS 7.0, *) {
-            _imageModel_SwiftUI = SwiftUI.StateObject(wrappedValue: imageModel)
-        } else {
-            _imageModel_Backport = Backport.StateObject(wrappedValue: imageModel)
-        }
+        _imageModel = ObservedObject(wrappedValue: imageModel)
     }
     
     #if os(macOS)
diff --git a/SDWebImageSwiftUI/Classes/ImageManager.swift b/SDWebImageSwiftUI/Classes/ImageManager.swift
@@ -28,37 +28,24 @@ public final class ImageManager : ObservableObject {
     /// true means during incremental loading
     @Published public var isIncremental: Bool = false
     
-    var manager: SDWebImageManager?
     weak var currentOperation: SDWebImageOperation? = nil
     
-    var url: URL?
-    var options: SDWebImageOptions = []
-    var context: [SDWebImageContextOption : Any]? = nil
     var successBlock: ((PlatformImage, Data?, SDImageCacheType) -> Void)?
     var failureBlock: ((Error) -> Void)?
     var progressBlock: ((Int, Int) -> Void)?
     
-    /// Create a image manager for loading the specify url, with custom options and context.
+    public init() {}
+    
+    /// Start to load the url operation
     /// - Parameter url: The image url
     /// - Parameter options: The options to use when downloading the image. See `SDWebImageOptions` for the possible values.
     /// - Parameter context: A context contains different options to perform specify changes or processes, see `SDWebImageContextOption`. This hold the extra objects which `options` enum can not hold.
-    public init(url: URL?, options: SDWebImageOptions = [], context: [SDWebImageContextOption : Any]? = nil) {
-        self.url = url
-        self.options = options
-        self.context = context
-        if let manager = context?[.customManager] as? SDWebImageManager {
-            self.manager = manager
+    public func load(url: URL?, options: SDWebImageOptions = [], context: [SDWebImageContextOption : Any]? = nil) {
+        let manager: SDWebImageManager
+        if let customManager = context?[.customManager] as? SDWebImageManager {
+            manager = customManager
         } else {
-            self.manager = .shared
-        }
-    }
-    
-    init() {}
-    
-    /// Start to load the url operation
-    public func load() {
-        guard let manager = manager else {
-            return
+            manager = .shared
         }
         if currentOperation != nil {
             return
diff --git a/SDWebImageSwiftUI/Classes/SwiftUICompatibility.swift b/SDWebImageSwiftUI/Classes/SwiftUICompatibility.swift
@@ -0,0 +1,84 @@
+/*
+ * This file is part of the SDWebImage package.
+ * (c) DreamPiggy <lizhuoli1126@126.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+import Foundation
+import SwiftUI
+
+#if os(iOS) || os(tvOS) || os(macOS)
+
+@available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
+struct PlatformAppear: PlatformViewRepresentable {
+    let appearAction: () -> Void
+    let disappearAction: () -> Void
+    
+    #if os(iOS) || os(tvOS)
+    func makeUIView(context: Context) -> some UIView {
+        let view = PlatformAppearView()
+        view.appearAction = appearAction
+        view.disappearAction = disappearAction
+        return view
+    }
+    
+    func updateUIView(_ uiView: UIViewType, context: Context) {}
+    #endif
+    #if os(macOS)
+    func makeNSView(context: Context) -> some NSView {
+        let view = PlatformAppearView()
+        view.appearAction = appearAction
+        view.disappearAction = disappearAction
+        return view
+    }
+    
+    func updateNSView(_ nsView: NSViewType, context: Context) {}
+    #endif
+}
+
+@available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
+class PlatformAppearView: PlatformView {
+    var appearAction: () -> Void = {}
+    var disappearAction: () -> Void = {}
+    
+    #if os(iOS) || os(tvOS)
+    override func willMove(toWindow newWindow: UIWindow?) {
+        if newWindow != nil {
+            appearAction()
+        } else {
+            disappearAction()
+        }
+    }
+    #endif
+    
+    #if os(macOS)
+    override func viewWillMove(toWindow newWindow: NSWindow?) {
+        if newWindow != nil {
+            appearAction()
+        } else {
+            disappearAction()
+        }
+    }
+    #endif
+}
+
+#endif
+
+@available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
+extension View {
+    /// Used UIKit/AppKit behavior to detect the SwiftUI view's visibility.
+    /// This hack is because of SwiftUI 1.0/2.0 buggy behavior. The built-in `onAppear` and `onDisappear` is so massive on some cases. Where UIKit/AppKit is solid.
+    /// - Parameters:
+    ///   - appear: The action when view appears
+    ///   - disappear: The action when view disappears
+    /// - Returns: Some view
+    func onPlatformAppear(appear: @escaping () -> Void = {}, disappear: @escaping () -> Void = {}) -> some View {
+        #if os(iOS) || os(tvOS) || os(macOS)
+        return self.background(PlatformAppear(appearAction: appear, disappearAction: disappear))
+        #else
+        return self.onAppear(perform: appear).onDisappear(perform: disappear)
+        #endif
+    }
+}
diff --git a/SDWebImageSwiftUI/Classes/WebImage.swift b/SDWebImageSwiftUI/Classes/WebImage.swift
@@ -9,6 +9,15 @@
 import SwiftUI
 import SDWebImage
 
+/// Data Binding Object, only properties in this object can support changes from user with @State and refresh
+@available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
+final class WebImageModel : ObservableObject {
+    /// URL image
+    @Published var url: URL?
+    @Published var webOptions: SDWebImageOptions = []
+    @Published var webContext: [SDWebImageContextOption : Any]? = nil
+}
+
 /// Completion Handler Binding Object, supports dynamic @State changes
 @available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
 final class WebImageHandler: ObservableObject {
@@ -43,6 +52,9 @@ public struct WebImage : View {
     /// True to start animation, false to stop animation.
     @Binding public var isAnimating: Bool
     
+    /// A observed object to pass through the image model to manager
+    @ObservedObject var imageModel: WebImageModel
+    
     /// A observed object to pass through the image handler to manager
     @ObservedObject var imageHandler = WebImageHandler()
     
@@ -52,25 +64,10 @@ public struct WebImage : View {
     /// A observed object to pass through the image manager loading status to indicator
     @ObservedObject var indicatorStatus = IndicatorStatus()
     
-    @SwiftUI.StateObject var imagePlayer_SwiftUI = ImagePlayer()
-    @Backport.StateObject var imagePlayer_Backport = ImagePlayer()
-    var imagePlayer: ImagePlayer {
-        if #available(iOS 14.0, macOS 11.0, tvOS 14.0, watchOS 7.0, *) {
-            return imagePlayer_SwiftUI
-        } else {
-            return imagePlayer_Backport
-        }
-    }
+    @ObservedObject var imagePlayer = ImagePlayer()
     
-    @SwiftUI.StateObject var imageManager_SwiftUI = ImageManager()
-    @Backport.StateObject var imageManager_Backport = ImageManager()
-    var imageManager: ImageManager {
-        if #available(iOS 14.0, macOS 11.0, tvOS 14.0, watchOS 7.0, *) {
-            return imageManager_SwiftUI
-        } else {
-            return imageManager_Backport
-        }
-    }
+    // FIXME: Use SwiftUI StateObject and remove onPlatformAppear once drop iOS 13 support
+    @Backport.StateObject var imageManager = ImageManager()
     
     /// Create a web image with url, placeholder, custom options and context. Optional can support animated image using Binding.
     /// - Parameter url: The image url
@@ -86,11 +83,11 @@ public struct WebImage : View {
                 context[.animatedImageClass] = SDAnimatedImage.self
             }
         }
-        if #available(iOS 14.0, macOS 11.0, tvOS 14.0, watchOS 7.0, *) {
-            _imageManager_SwiftUI = SwiftUI.StateObject(wrappedValue: ImageManager(url: url, options: options, context: context))
-        } else {
-            _imageManager_Backport = Backport.StateObject(wrappedValue: ImageManager(url: url, options: options, context: context))
-        }
+        let imageModel = WebImageModel()
+        imageModel.url = url
+        imageModel.webOptions = options
+        imageModel.webContext = context
+        _imageModel = ObservedObject(wrappedValue: imageModel)
     }
     
     /// Create a web image with url, placeholder, custom options and context.
@@ -128,24 +125,24 @@ public struct WebImage : View {
                 }
             } else {
                 setupPlaceholder()
-                .onAppear {
+                .onPlatformAppear(appear: {
                     self.imageManager.successBlock = self.imageHandler.successBlock
                     self.imageManager.failureBlock = self.imageHandler.failureBlock
                     self.imageManager.progressBlock = self.imageHandler.progressBlock
                     // Load remote image when first appear
-                    self.imageManager.load()
+                    self.imageManager.load(url: imageModel.url, options: imageModel.webOptions, context: imageModel.webContext)
                     guard self.imageConfiguration.retryOnAppear else { return }
                     // When using prorgessive loading, the new partial image will cause onAppear. Filter this case
                     if self.imageManager.image == nil && !self.imageManager.isIncremental {
-                        self.imageManager.load()
+                        self.imageManager.load(url: imageModel.url, options: imageModel.webOptions, context: imageModel.webContext)
                     }
-                }.onDisappear {
+                }, disappear: {
                     guard self.imageConfiguration.cancelOnDisappear else { return }
                     // When using prorgessive loading, the previous partial image will cause onDisappear. Filter this case
                     if self.imageManager.image == nil && !self.imageManager.isIncremental {
                         self.imageManager.cancel()
                     }
-                }.onReceive(imageManager.objectWillChange) { _ in
+                }).onReceive(imageManager.objectWillChange) { _ in
                     indicatorStatus.isLoading = imageManager.isLoading
                     indicatorStatus.progress = imageManager.progress
                 }
@@ -228,7 +225,7 @@ public struct WebImage : View {
         // Don't use `Group` because it will trigger `.onAppear` and `.onDisappear` when condition view removed, treat placeholder as an entire component
         if let placeholder = placeholder {
             // If use `.delayPlaceholder`, the placeholder is applied after loading failed, hide during loading :)
-            if imageManager.options.contains(.delayPlaceholder) && imageManager.isLoading {
+            if imageModel.webOptions.contains(.delayPlaceholder) && imageManager.isLoading {
                 return AnyView(configure(image: .empty))
             } else {
                 return placeholder
diff --git a/Tests/ImageManagerTests.swift b/Tests/ImageManagerTests.swift
@@ -18,7 +18,7 @@ class ImageManagerTests: XCTestCase {
     func testImageManager() throws {
         let expectation = self.expectation(description: "ImageManager usage with Combine")
         let imageUrl = URL(string: "https://via.placeholder.com/500x500.jpg")
-        let imageManager = ImageManager(url: imageUrl)
+        let imageManager = ImageManager()
         imageManager.setOnSuccess { image, cacheType, data in
             XCTAssertNotNil(image)
             expectation.fulfill()
@@ -29,7 +29,7 @@ class ImageManagerTests: XCTestCase {
         imageManager.setOnProgress { receivedSize, expectedSize in
             
         }
-        imageManager.load()
+        imageManager.load(url: imageUrl)
         XCTAssertNotNil(imageManager.currentOperation)
         let sub = imageManager.objectWillChange
             .subscribe(on: RunLoop.main)
