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SubView。

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

我能做这样的事吗？如果是，我怎么能？

Answer 1

如果视图包含BaseView，那么它绝对不是与之相关的子视图。并且，由于违反了单一的真实性来源，您不应该访问/操纵其他视图的内部状态。

相反，您必须在这种情况下使用绑定，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
}
}
}