如何在 SubView SwiftUI 中使用 BaseView @State 属性

Question

我有一个类似这样的 BaseView，我想为我的所有子视图添加警报机制

struct BaseView<Content: View>: View {
    @State var isAlertPresented = false
    let content: Content
    
    init(@ViewBuilder content: () -> Content) {
        self.content = content()
    }
    
    var body : some View {
        content.alert(isPresented: $isAlertPresented) {
            Alert(title: Text("title"))
        }
    }

}

这是我的子视图。

struct SubView: View {
    BaseView {
        Text("")
    }.onReceive(vm.publisher) { (output) in
        // here I want to trigger BaseView isAlertPresented property        
        // BaseView.isAlertPresented = true
    }
}

我可以做这样的事情吗？如果可以，我该怎么办？

Answer 1

如果视图包含BaseView，那么它肯定不是与其相关的子视图。由于 single-source-of-truth 违规，您不应该 access/manipulate 其他视图的内部状态。

相反，您必须在这种情况下使用 Binding，如下所示（使用 Xcode 11.7 测试）

struct BaseView<Content: View>: View {
    @Binding var isAlertPresented: Bool
    let content: Content

    init(isAlertPresented: Binding<Bool>, @ViewBuilder content: () -> Content) {
        self._isAlertPresented = isAlertPresented
        self.content = content()
    }

    var body : some View {
        content.alert(isPresented: $isAlertPresented) {
            Alert(title: Text("title"))
        }
    }

}

struct SomeOtherView: View {
    @State private var showAlert = false

    var body: some View {
        BaseView(isAlertPresented: $showAlert) {
            Text("Test")
        }
        .onReceive(vm.publisher) { (output) in
//        .onAppear {     // used instead of above just for test
            self.showAlert = true
        }
    }
}

如何在 SubView SwiftUI 中使用 BaseView @State 属性

How to use BaseView @State property in SubView SwiftUI

swift

swiftui

viewbuilder