SwiftUI:如何在工作表关闭后显示警报? [英] SwiftUI: How to show an alert after a sheet is closed?

问题描述

我正在尝试显示由模式表触发的警报.这是一个小型演示项目:

I'm trying to show an alert which is triggered by a modal sheet. Here's a small demo project:

import SwiftUI

struct ContentView: View {
    @State private var showSheet = false
    @State private var showAlert = false

    var body: some View {
        Button("Press") {
            showSheet = true
        }
        .sheet(isPresented: $showSheet) {
            Button("Close with alert") {
                showSheet = false
                showAlert = true
            }
        }
        .alert(isPresented: $showAlert) {
            Alert(title: Text("Alert"))
        }
    }
}

点击按"后按钮，会出现一个带有Close with alert"按钮的模式表.如果按下此按钮，工作表将关闭并且没有任何反应.我希望显示警报.

After clicking on the "Press" button, a modal sheet appears with a button "Close with alert". If this button is pressed the sheet closes and nothing happens. I expect to have the alert shown.

似乎是隐藏工作表的动画导致了这个问题，因为在设置 showSheet = false 后，SwiftUI 似乎并不认为工作表已关闭.出现以下警告，支持该理论:

It seems that the animation of hiding the sheet is causing the issue as SwiftUI doesn't seem to consider the sheet as closed after setting showSheet = false. The following warning appears which is supporting this theory:

[Presentation] 尝试展示 <SwiftUI.PlatformAlertController:0x7fbbab012200>在<TtGC7SwiftUI19UIHostingControllerGVS_15ModifiedContentVS_7AnyViewVS_12RootModifier_:0x7fbbaa60b7d0>(从<TtGC7SwiftUI19UIHostingControllerGVS_15ModifiedContentVS_7AnyViewVS_12RootModifier_:0x7fbbaa60b7d0>) 已经呈现<TtGC7SwiftUI22SheetHostingControllerVS_7AnyView:0x7fbbaa413200>.

[Presentation] Attempt to present <SwiftUI.PlatformAlertController: 0x7fbbab012200> on <TtGC7SwiftUI19UIHostingControllerGVS_15ModifiedContentVS_7AnyViewVS_12RootModifier_: 0x7fbbaa60b7d0> (from <TtGC7SwiftUI19UIHostingControllerGVS_15ModifiedContentVS_7AnyViewVS_12RootModifier_: 0x7fbbaa60b7d0>) which is already presenting <TtGC7SwiftUI22SheetHostingControllerVS_7AnyView: 0x7fbbaa413200>.

推荐答案

您可以使用onDismiss.

以下是一些基于何时您想显示警报的示例:

Here are some examples based on when do you want to present an alert:

1. 总是以提醒关闭:

1. Always close with an alert:

struct ContentView: View {
    @State private var showSheet = false
    @State private var showAlert = false

    var body: some View {
        Button("Press") {
            showSheet = true
        }
        .sheet(isPresented: $showSheet, onDismiss: {
            showAlert = true
        }) {
            Button("Close") {
                showSheet = false
            }
        }
        .alert(isPresented: $showAlert) {
            Alert(title: Text("Alert"))
        }
    }
}

1. 关闭并在仅点击按钮时发出警报:

1. Close with an alert on button click only:

struct ContentView: View {
    @State private var showSheet = false
    @State private var showAlert = false
    @State private var closeSheetWithAlert = false

    var body: some View {
        Button("Press") {
            showSheet = true
            closeSheetWithAlert = false
        }
        .sheet(isPresented: $showSheet, onDismiss: {
            showAlert = closeSheetWithAlert
        }) {
            Button("Close") {
                closeSheetWithAlert = true
                showSheet = false
            }
        }
        .alert(isPresented: $showAlert) {
            Alert(title: Text("Alert"))
        }
    }
}

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