[英]SwiftUI: How to change the image for a selected item in TabbedView
[英]How to change an image to a structure? SwiftUI
現在,當應用程序打開時,會顯示鏈接中的圖像,但如果用戶沒有互聯網,則會顯示我的應用程序文件中的圖像
如果用戶沒有互聯網連接,如何代替我的圖像 - 名稱:“noconnection”,顯示我的結構:Indicator()。
我的代碼:
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
}
}
}
}
我的結構 - Indicator() - 代碼
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) {
//
}
}
此結構 - Indicator() - 應顯示而不是圖像“noconnection”
我將不勝感激任何幫助
您可以更改failure
類型以接受Indicator
。 然后,將您的selectImage
更改為返回some View
的@ViewBuilder
:
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
}
}
}
}
在這種情況下,您可能想要擺脫默認參數並只設置var failure = Indicator()
而不是使用初始值設定項
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