SwiftUI @State 和 .sheet() ios13 与 ios14

问题描述

您好，我在这里遇到了一个问题，在 ios13 或 ios14 上运行时，我的 .sheet() 视图之间没有一致的行为

Hello I am running into a problem here and I do not have a consistent behavior between my .sheet() view when running on ios13 or ios14

我有这样的看法:

@State private var label: String = ""
@State private var sheetDisplayed = false
///Some code
var body: some View {
   VStack {
      Button(action: {
         self.label = "A label"
         self.isDisplayed = true
      }) {
           Text("test")
       }
   }.sheet(isPresented: $sheetDisplayed, onDismiss: {
        self.label = ""
    }) {
        Text(self.label)
       }
 }

在 ios 13 上按预期工作 btn click ->设置标签 ->呼叫表 ->显示A标签"在文本视图中.

On ios 13 this work as expected btn click -> set label -> call sheet -> display "A label" in a Text view.

在 ios14 上，我在工作表关闭时在 self.label 中得到一个空字符串，因此它不显示任何内容.

On ios14 I got an empty string in self.label when in sheet closure, hence it does not display anything.

我错过了什么吗?这是 iOS 14 的错误还是我在 ios13 上的错误并得到了纠正.

Did I missed something ? Is it an iOS 14 bug or did I had it wrong on ios13 and that got corrected.

PS:我在我简化的闭包中传递了一些其他变量.

PS: I have a couple of other variables that are passed in the closure I simplified it.

推荐答案

您的代码期望视图更新/创建顺序，但通常它是未定义的(并且可能在 iOS 14 中更改).

Your code have expectation of view update/creation order, but in general it is undefined (and probably changed in iOS 14).

有明确的方式在工作表内传递信息 - 使用不同的工作表创建者，即..sheet(item:...

There is explicit way to pass information inside sheet - use different sheet creator, ie. .sheet(item:...

这是一个可靠的例子.使用 Xcode 12/iOS 14 测试

Here is working reliable example. Tested with Xcode 12 / iOS 14

struct ContentView: View {
    @State private var item: Item?

    struct Item: Identifiable {
        let id = UUID()
        var label: String = ""
    }

    var body: some View {
        VStack {
            Button(action: {
                self.item = Item(label: "A label")
            }) {
                Text("test")
            }
        }.sheet(item: $item, onDismiss: {
            self.item = nil
        }) {
            Text($0.label)
        }
    }
}

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