如何将图像更改为结构？斯威夫特用户界面

Question

现在，当应用程序打开时，会显示来自 link 的图像，但如果用户没有互联网，则会显示来自我的应用程序文件的图像

如何代替我的图像 - 名称：“noconnection”，显示我的结构：Indicator() 如果用户没有互联网连接。

我的代码：

struct RemoteImage: View {

    private enum LoadState {
        case loading, success, failure
    }

    private class Loader: ObservableObject {
            var data = Data()
            var state = LoadState.loading

            init(url: String) {
                guard let parsedURL = URL(string: url) else {
                    fatalError("Invalid URL: \(url)")
                }

                URLSession.shared.dataTask(with: parsedURL) { data, response, error in
                    if let data = data, data.count > 0 {
                        self.data = data
                        self.state = .success
                    } else {
                        self.state = .failure
                    }

                    DispatchQueue.main.async {
                                        self.objectWillChange.send()
                                    }
                                }.resume()
                            }
                        }

    @StateObject private var loader: Loader
     var loading: Image
     var failure: Image

     var body: some View {
         selectImage()
             .resizable()
     }

    init(url: String, loading: Image = Image("loadingimage"), failure: Image = Image("noconnection")) {
         _loader = StateObject(wrappedValue: Loader(url: url))
         self.loading = loading
         self.failure = failure
     }

     private func selectImage() -> Image {
         switch loader.state {
         case .loading:
             return loading
         case .failure:
             return failure
         default:
             if let image = UIImage(data: loader.data) {
                return Image(uiImage: image).resizable()
             } else {
                 return failure
             }
         }
     }
 }

我的结构 - Indicator() - 代码

struct Indicator : UIViewRepresentable {
    func makeUIView(context: Context) -> UIActivityIndicatorView {
        let indicator = UIActivityIndicatorView()
        indicator.startAnimating()
        indicator.style = .large
        indicator.color = .systemTeal
        
        return indicator
    }
    
    func updateUIView(_ uiView: UIActivityIndicatorView, context: Context) {
        //
    }
}

应显示此结构 - Indicator() - 而不是图像“noconnection”

如有任何帮助，我将不胜感激

Answer 1

您可以更改 failure 类型以接受 Indicator。然后，将 selectImage 更改为 @ViewBuilder returns some View:


struct RemoteImage: View {
    
    private enum LoadState {
        case loading, success, failure
    }
    
    private class Loader: ObservableObject {
        var data = Data()
        var state = LoadState.loading
        
        init(url: String) {
            guard let parsedURL = URL(string: url) else {
                fatalError("Invalid URL: \(url)")
            }
            
            URLSession.shared.dataTask(with: parsedURL) { data, response, error in
                if let data = data, data.count > 0 {
                    self.data = data
                    self.state = .success
                } else {
                    self.state = .failure
                }
                
                DispatchQueue.main.async {
                    self.objectWillChange.send()
                }
            }.resume()
        }
    }
    
    @StateObject private var loader: Loader
    var loading: Image
    var failure: Indicator
    
    var body: some View {
        selectImage()
    }
    
    init(url: String, loading: Image = Image("loadingimage").resizable(), failure: Indicator = Indicator()) {
        _loader = StateObject(wrappedValue: Loader(url: url))
        self.loading = loading
        self.failure = failure
    }
    
    @ViewBuilder private func selectImage() -> some View {
        switch loader.state {
        case .loading:
            loading
        case .failure:
            failure
        default:
            if let image = UIImage(data: loader.data) {
                Image(uiImage: image).resizable()
            } else {
                failure
            }
        }
    }
}

在这种情况下，您可能希望摆脱默认参数并设置 var failure = Indicator() 而不是使用初始化程序

如何将图像更改为结构？斯威夫特用户界面

How to change an image to a structure? SwiftUI

xcode

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ios15