SwiftUI @State var 初始化问题 [英] SwiftUI @State var initialization issue

问题描述

我想通过 Struct 的 init() 方法在 SwiftUI 中初始化 @State var 的值，所以它可以从准备好的字典中获取正确的文本，以便在 TextField 中进行操作.源代码如下所示:

I would like to initialise the value of a @State var in SwiftUI through the init() method of a Struct, so it can take the proper text from a prepared dictionary for manipulation purposes in a TextField. The source code looks like this:

struct StateFromOutside: View {
    let list = [
        "a": "Letter A",
        "b": "Letter B",
        // ...
    ]
    @State var fullText: String = ""

    init(letter: String) {
        self.fullText = list[letter]!
    }

    var body: some View {
        TextField($fullText)
    }
}

不幸的是，执行失败并出现错误 Thread 1: Fatal error: Accessing State外部 View.body

Unfortunately the execution fails with the error Thread 1: Fatal error: Accessing State<String> outside View.body

我该如何解决这种情况?预先非常感谢您！

How can I resolve the situation? Thank you very much in advance!

推荐答案

我会尝试在 onAppear 中初始化它.

I would try to initialise it in onAppear.

struct StateFromOutside: View {
    let list = [
        "a": "Letter A",
        "b": "Letter B",
        // ...
    ]
    @State var fullText: String = ""

    var body: some View {
        TextField($fullText)
             .onAppear {
                 self.fullText = list[letter]!
             }
    }
}

或者，更好的是，使用模型对象(链接到您的视图的 BindableObject)并在那里完成所有初始化和业务逻辑.您的视图将更新以自动反映更改.

Or, even better, use a model object (a BindableObject linked to your view) and do all the initialisation and business logic there. Your view will update to reflect the changes automatically.

更新:BindableObject 现在更名为 ObservableObject.

Update: BindableObject is now called ObservableObject.

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