SwiftUI |如何覆盖像viewWillAppear这样的生命周期方法

创建自己的容器视图。你可以用 @ViewBuilder VStack HStack 它需要一个充满子视图的内容闭包。

import SwiftUI

struct CustomContainer<Content: View>: View {
    init(@ViewBuilder content: () -> Content) {
        self.content = content()
    }

    let content: Content

    var body: some View {
        VStack(spacing: 0) {
            content
                .frame(maxWidth: .infinity, maxHeight: .infinity)
                .background(Color(hue: 0, saturation: 0.3, brightness: 1))
            Toolbar()
        }
    }
}

struct Toolbar: View {
    var body: some View {
        HStack {
            Spacer()
            button("person.3.fill")
            Spacer()
            button("printer.fill")
            Spacer()
            button("heart.fill")
            Spacer()
            button("bubble.left.fill")
            Spacer()
        } //
            .frame(height: 44)
    }

    private func button(_ name: String) -> some View {
        Image(systemName: name)
            .resizable()
            .aspectRatio(contentMode: .fit)
            .padding(4)
            .frame(width: 40, height: 40)
    }
}

下面是一个使用它的视图:

struct HelloView: View {
    var body: some View {
        CustomContainer {
            VStack {
                Text("hello")
                Text("khawar")
            }
        }
    }
}

import PlaygroundSupport
PlaygroundPage.current.setLiveView(HelloView())