问题描述
我想弄清楚如何在 SwiftUI 中使用 @State 和 fullScreenCover 在视图之间切换
我有一个主视图和 2 个简单视图(View1
和 View2
)。 View1
必须在点击 "Show view 1"
按钮时打开,而在 View2
按钮上输入时必须打开 "Show view 2"
。我还为此创建了 2 个 @State
变量,并使用 .View1
(ActiveFullscreenview
枚举)对其进行了初始化:
@State private var showFullscreenView = false
@State private var activeFullscreenView: ActiveFullscreenView = .View1
问题在于,即使我点击 View1
按钮,它也会不断显示 Show view 2
。
我认为当点击按钮并给 activeFullscreenView 变量赋值 .View2
时,它应该改变变量并显示 fullScreenView
。
我认为这是因为我调用了 showFullscreenView
并且它改变了变量,之后默认值是 .View1
所以它没有改变它。
也试过了:
self.showFullscreenView = true
self.activeFullscreenView = .View2
第二个假设是我不应该给这个变量初始值。但在这种情况下,它添加了一些不方便的额外初始化代码:
@State private var activeFullscreenView: ActiveFullscreenView = .View1
import SwiftUI
struct MainView: View {
enum ActiveFullscreenView {
case View1,View2
}
@State private var showFullscreenView = false
@State private var activeFullscreenView: ActiveFullscreenView = .View1
var body: some View {
ZStack {
vstack {
// Button to show View 1 in FullScreen
Button("Show view 1",action: {
self.activeFullscreenView = .View1
self.showFullscreenView = true
})
// Button to show View 2 in FullScreen
Button("Show view 2",action: {
self.activeFullscreenView = .View2
self.showFullscreenView = true
})
}
}
.fullScreenCover(isPresented: $showFullscreenView) {
switch self.activeFullscreenView {
case .View1:
Text("View1")
case .View2:
Text("View2")
}
}
}
}
struct MainView_Previews: PreviewProvider {
static var previews: some View {
MainView()
}
}
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使用 Xcode 12.4,最新的 iOS 14
解决方法
在@jnpdx 的帮助下 This Answer that is Similar to My problem 问题解决了。这是代码。只要 fullScreenCover 和 sheet 都是模态,我将 enum 重命名为 ModalView:
struct MainView: View {
// enum to decide which view to present:
enum ModalView: String,Identifiable { // Identifiable
case View1,View2
var id: String {
return self.rawValue
}
}
@State var activeModalView : ModalView? = nil
var body: some View {
ZStack {
VStack {
// Button to show View 1
Button("Show view 1",action: {
self.activeModalView = .View1
})
// Button to show View 2
Button("Show view 2",action: {
self.activeModalView = .View2
})
}
} // use fullScreenCover or sheet depending on your needs
.fullScreenCover(item: $activeModalView) { activeModalValue in
switch activeModalValue {
case .View1:
Text("View1")
case .View2:
Text("View2")
}
}
}
}