تكييف حل عملك الحالي مع SwiftUI. الجزء 2

• SDWebImageDownloader
• SDImageCache

• من خلال تمرير روابط ضعيفة إلى نفس UIImageView ؛
• بتمرير كتلة الإغلاق إلى طريقة ImageManager

extension UIImageView {
 func setup(by key: String) {
        ImageManager.sharedInstance.setImage(toImageView: self, forKey: key)
    }
}

class CachedImageView : UIImageView {
    private var _imageUrl: String?
    var imageUrl: String?  {
        get {
            return _imageUrl
        }
        set {
            self._imageUrl = newValue
            if let url = newValue, !url.isEmpty {
                self.setup(by: url)
            }
        }
    }
    
    func setup(by key: String) {
        ImageManager.sharedInstance.setImage(toImageView: self, forKey: key)
    }
}

• جعل؛
• تحديث

struct WrappedCachedImage : UIViewRepresentable {
    let height: CGFloat
    @State var imageUrl: String
    
    func makeUIView(context: Context) -> CachedImageView {
        let frame = CGRect(x: 20, y: 0, width: UIScreen.main.bounds.size.width - 40, 
                                     height: height)
        return CachedImageView(frame: frame)
    }
    
    func updateUIView(_ uiView: CachedImageView, context: Context) {
        uiView.imageUrl = imageUrl
        uiView.contentMode = .scaleToFill
    }
}

• لا حاجة لتغيير عمل مكتبة موجودة
• يتم تغليف المنطق في UIView المضمنة.

 var body: some View {
      GeometryReader { geometry in 
        VStack {
           WrappedCachedImage(height:300, imageUrl: imageUrl) 
           .frame(minWidth: 0, maxWidth: geometry.size.width,
                     minHeight: 0, maxHeight: 300)
        }
    }
}

• إنشاء عرض مخصص ، والذي سنستخدم فيه تحكم SwiftUI ؛
• إنشاء ViewModel ننقل منه منطق العمل مع Model (ImageManager).

class CachedImageModel : ObservableObject {
    @Published var image: UIImage = UIImage()
    
    private var urlString: String = ""
    
    init(urlString:String) {
        self.urlString = urlString
    }
    
    func loadImage() {
        ImageManager.sharedInstance
        .receiveImage(forKey: urlString) {[weak self] (im) in
            guard let self = self else {return}
            DispatchQueue.main.async {
                self.image = im
            }
        }
    }
}

struct CachedLoaderImage : View {
    @ObservedObject var  model:CachedImageModel
    
    init(withURL url:String) {
        self.model = CachedImageModel(urlString: url)
    }
    
    var body: some View {
        Image(uiImage: model.image)
            .resizable()
            .onAppear{
                self.model.loadImage()
        }
    }
    
}

class ImageLoader: ObservableObject {
 @Published var image: UIImage?
 private var cancellable: AnyCancellable?

 func load(url: String) {
     cancellable = ImageManager.sharedInstance.publisher(for: url)
         .map { UIImage(data: $0.data) }
         .replaceError(with: nil)
         .receive(on: DispatchQueue.main)
         .assign(to: \.image, on: self)
 }

    var didChange = PassthroughSubject<UIImage, Never>()

var data = UIImage() {
        didSet {
            didChange.send(data)
        }
    }
 ,    .

 var body: some View {
       Image(uiImage: image)
            .onReceive(imageLoader.didChange) { im in
            self.image = im
           //-   
        }
    }