将参数传递给 SwiftUI 表 [英] passing parameter to a SwiftUI Sheet

问题描述

我需要将参数 calledFrom 传递给 SwiftUI 中的工作表.
奇怪的是，该参数在第一次调用时没有使用，但在接下来的调用中有效.

导入 SwiftUI结构内容视图:查看{@State var showSheet = false@State var calledFrom = -1var主体:一些视图{ForEach((1...4), id: \.self) { i in获取按钮(i)}.sheet(isPresented: $showSheet) { Dialog(CalledFrom: calledFrom) }.填充()}func getButton(_ i : Int) ->一些视图{return Button("\(i)"){print("Button \(i)pressed");调用自 = i;showSheet = true }}}结构对话框:查看{var callFrom : Int@Environment(\.presentationMode) 私有变量presentationModevar主体:一些视图{虚拟堆栈{Text("从按钮调用\(callFrom)")按钮(关闭"){presentationMode.wrappedValue.dismiss()}}.填充()}}

解决方案

您必须使用 sheet(item:) 来获得您正在寻找的行为.在 iOS 14 中，sheet 视图是在@State 改变之前计算的:

<预><代码>struct ActiveItem:可识别{调用自变量:Intvar id: Int { return calledFrom }}结构内容视图:查看{@State var activeItem :ActiveItem?var主体:一些视图{ForEach((1...4), id: \.self) { i in获取按钮(i)}.sheet(item: $activeItem) { item in对话框(调用自:item.CalledFrom)}.填充()}func getButton(_ i : Int) ->一些视图{返回按钮(\(i)"){打印(按钮\(i)按下")；activeItem = ActiveItem(callFrom: i)}}}

I need to pass a parameter calledFrom to a Sheet in SwiftUI.
Strangely, the parameter is not used on the first call, but it works on the following ones.

import SwiftUI

struct ContentView: View {
    @State var showSheet = false
    @State var calledFrom = -1
    
    var body: some View {
        ForEach((1...4), id: \.self) { i in
            getButton(i)
        }
        .sheet(isPresented: $showSheet) { Dialog(calledFrom: calledFrom) }
        .padding()
    }
    
    func getButton(_ i : Int) -> some View {
        return Button("\(i)"){print("Button \(i) pressed"); calledFrom = i; showSheet = true }
    }
}

struct Dialog: View {
  var calledFrom : Int
  @Environment(\.presentationMode) private var presentationMode
  var body: some View {
    VStack{
      Text("Called from Button \(calledFrom)")
        Button("close"){presentationMode.wrappedValue.dismiss()}
    }
    .padding()
  }
}

解决方案

You have to use sheet(item:) to get the behavior you're looking for. In iOS 14, the sheet view is calculated before the @State changes:

struct ActiveItem : Identifiable {
    var calledFrom: Int
    var id: Int { return calledFrom }
}

struct ContentView: View {
    @State var activeItem : ActiveItem?
    
    var body: some View {
        ForEach((1...4), id: \.self) { i in
            getButton(i)
        }
        .sheet(item: $activeItem) { item in
            Dialog(calledFrom: item.calledFrom)
        }
        .padding()
    }
    
    func getButton(_ i : Int) -> some View {
        return Button("\(i)"){
            print("Button \(i) pressed");
            activeItem = ActiveItem(calledFrom: i)
        }
    }
}

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