SwiftUI中出现键盘时，OnAppear意外调用 [英] OnAppear calls unexpectedly when Keyboard Appears in SwiftUI

问题描述

我在SwiftUI 2.0和iOS14中遇到了非常奇怪的行为.

I am experiencing very odd behavior in SwiftUI 2.0 and iOS14.

当键盘出现在屏幕上时，其他选项卡视图的OnAppear方法将自动调用.

When the keyboard appears on the screen, the OnAppear method of other tab's view called automatically.

但是，这在Xcode 11.7上正常工作

However, this works fine Xcode 11.7

这是行动中的问题.

这里是产生上述错误的代码.

Here is the code which produces the above error.

struct ContentView: View {
    var body: some View {
        TabView {
            DemoView(screenName: "Home")
                .tabItem {
                    Image.init(systemName: "star.fill")
                    Text("Home")
                }
            DemoView(screenName: "Result")
                .tabItem {
                    Image.init(systemName: "star.fill")
                    Text("Result")
                }
            DemoView(screenName: "More")
                .tabItem {
                    Image.init(systemName: "star.fill")
                    Text("More")
                }
        }
    }
}

struct DemoView:View {
    
    @State var text:String = ""
    var screenName:String
    var body: some View {
        VStack{
            Text(screenName)
                .font(.title)
            
            TextField("Buggy Keyboard Issue", text: $text)
                .textFieldStyle(RoundedBorderTextFieldStyle())
                
            Text("Issue : When keyboard appears, onAppear of other 2 tabs call automatically.")
                .font(.footnote)
        }
        .padding()
        .onAppear(perform: {
            debugPrint("OnAppear of : \(screenName)")
        })
    }
}

这似乎是SwiftUI 2.0的错误，但不确定.任何帮助将不胜感激.

This seems to be a bug of SwiftUI 2.0 but not sure. Any help will be appreciated.

谢谢

推荐答案

我自己也遇到了同样的问题，我认为这是一个错误或类似的问题，但是我想出了一个解决方案，直到苹果将其修复.

Having the same issue myself, I think this is a bug or something like that, however I came up with a solution maybe a workaround until apple will fix it.

我所做的基本上是使用 LazyVStack ，这似乎运行得很好.

The thing that I did is basically I used a LazyVStack, and this seems to be working perfectly.

LazyVStack {
    VStack{
        Text(screenName)
            .font(.title)
        
        TextField("Buggy Keyboard Issue", text: $text)
            .textFieldStyle(RoundedBorderTextFieldStyle())
            
        Text("Issue : When keyboard appears, onAppear of other 2 tabs call automatically.")
            .font(.footnote)
    }
    .padding()
    .onAppear(perform: {
        debugPrint("OnAppear of : \(screenName)")
})
}

现在其他选项卡视图的 OnAppear 方法在出现键盘时不会自动调用.

Now the OnAppear method of other tab's view it is not called automatically when the keyboard appear.

这篇关于SwiftUI中出现键盘时，OnAppear意外调用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！