Alert in SwiftUI

Alert作为音讯提示的一种方式也是非常方便有用的。当然它的运用方式也很简单。咱们一起来看看。

单个按钮的Alert

只有一个承认按钮和标题，当咱们点击Alert Button时会弹出如下款式的alert

struct AlertSample: View {
    @State private var showAlert: Bool = false
    @State private var backgronudColor: Color = .white
    var body: some View {
        ZStack {
            backgronudColor
                .edgesIgnoringSafeArea(.all)
            VStack {
                Button("Alert Button") {
                    showAlert.toggle()
                }
                .foregroundColor(Color.black)
            }
            .alert("Message", isPresented: $showAlert) {
                Button(role: .cancel) {} label: {
                    Text("Cancel")
                }
            }
        }
    }
}

单个按钮带有子音讯的Alert

只需把上述代码改成一下代码就能够完成有子音讯的alert，作用如下

struct AlertSample: View {
    @State private var showAlert: Bool = false
    @State private var backgronudColor: Color = .white
    var body: some View {
        ZStack {
            backgronudColor
                .edgesIgnoringSafeArea(.all)
            VStack {
                Button("Alert Button") {
                    showAlert.toggle()
                }
                .foregroundColor(Color.black)
            }
            .alert("Message", isPresented: $showAlert) {
                Button(role: .cancel) {} label: {
                    Text("Cancel")
                }
            } message: {
                Text("This is Swftui sample")
            }
        }
    }
}

双按钮的Alert

.alert("Message", isPresented: $showAlert) {
                Button(role: .cancel) {} label: {
                    Text("Cancel")
                }
                Button(role: .destructive) {
                    backgronudColor = .red
                } label: {
                    Text("Delete")
                }
            } message: {
                Text("This is Swftui sample")
            }

alert办法的界说中，actions能够有多个值。办法界说如下：

public func alert<A, M>(_ titleKey: LocalizedStringKey,
   isPresented: Binding<Bool>, 
  @ViewBuilder actions: () -> A,
   @ViewBuilder message: () -> M
) -> some View where A : View, M : View

以上代码作用如下：

运用传递值来显现音讯

这个是什么意思呢？咱们先来看看办法界说

public func alert<A, M, T>(_ titleKey: LocalizedStringKey,
isPresented: Binding<Bool>, 
presenting data: T?, 
@ViewBuilder actions: (T) -> A, 
@ViewBuilder message: (T) -> M
) -> some View where A : View, M : View

其间presenting便是咱们需要用来显现在message中的值，尤其当你需要动态删除某些数据之前，对特定数据做提示时就需要用到这个办法。

struct AlertSample: View {
    @State private var showAlert: Bool = false
    @State private var backgronudColor: Color = .white
    @State var name: String = ""
    var body: some View {
        ZStack {
            backgronudColor
                .edgesIgnoringSafeArea(.all)
            VStack {
                Button("Alert Button") {
                    name = "狂徒东北吴彦祖"
                    showAlert.toggle()
                }
                .foregroundColor(Color.black)
            }
            .alert(
                "Message",
                isPresented: $showAlert,
                presenting: name
            ) { str in
                Button(role: .cancel) {} label: {
                    Text("撤销")
                }
                Button(role: .destructive) {
                    backgronudColor = .red
                } label: {
                    Text("拉黑")
                }
            } message: { str in
                Text("你去确定要拉黑(name)吗？")
            }
        }
    }
}

作用如下：

以上便是alert的根本运用。

我们有什么观点呢？欢迎留言评论。
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