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foreach - In swiftui foreach onAppear Issue

问题描述

Here is my sample. I have a list with something to sum up. And I set up an Observe obj to store the result, trigger +1 when the subview on Appear. 

class observed : ObservableObject {

@Published var listNum : Int = 0

}

struct ContentView: View {

@State private var mylist = [
    1,0,1,0,1,1
]

var body: some View {

    ForEach(mylist, id: \.self) { (value) in
        ExtractedView(value:value)
     }

    }
}


struct ExtractedView: View {

  var value : Int = 0

  @EnvironmentObject var obj : observed

  @State var listNum:String = "0"

  var body: some View {
      Text(listNum)
        .onAppear{

          if self.value != 1{
              self.obj.listNum = 0
          }else{
              self.obj.listNum += 1
          }
          self.listNum = String(self.obj.listNum)

        }
     }
  }

But the result always Upside down, not as expected.

标签： foreachswiftui

解决方案

实际上.onAppear调用顺序是未定义的，因此不清楚预期的内容。无论如何，从我在提供的代码中看到的内容可能会混淆ForEachid，因为使用了数组值，但它不是唯一的。

尝试以下

ForEach(Array(mylist.enumerated()), id: \.0) { (i, value) in
    ExtractedView(value:value)
 }

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