如何设置相同类型的多个EnvironmentObjects [英] How to set multiple EnvironmentObjects which are same type

问题描述

我发现了这个问题 SwiftUI:将多个BindableObjects放入环境a>

I found this question SwiftUI: Putting multiple BindableObjects into Envionment

答案说，environmentObject(ObservableObject)返回修改后的视图，因此我可以为多个环境对象建立调用链.

the answer said environmentObject(ObservableObject) returns modified view, therefore I can make call chain for multiple environmentObject.

喜欢

let rootView = ContentView()
     .environmentObject(firstBindable)
     .environmentObject(secondBindable)

，我想知道firstBindable和secondBindable是同一类型会导致什么结果. .environmentObject()如何知道什么是exect值，这是程序员打算在 firstBindable 和 secondBindable 之间设置的值.

and I wonder what is result if firstBindable and secondBindable are same type. how .environmentObject() knows what is exect value which is a programmer intended to set between firstBindable and secondBindable.

所以我对此进行了测试

1. 我制作了一个ObservableObject类

final class TempStr: ObservableObject {
    @Published var tmpStr = "temp"

    init(initStr: String) {
        tmpStr = initStr
    }
}

1. 来自sceneDelegate的environmentObject的调用链

window.rootViewController
  = UIHostingController(rootView:
      TestView()
        .environmentObject(TempStr(initStr: "1st")) 
        .environmentObject(TempStr(initStr: "2nd"))

1. 以及View中使用的值

struct TestView: View {
  @EnvironmentObject var tmp1: TempStr
  @EnvironmentObject var tmp2: TempStr

   var body: some View {
      Text(tmp1.tmpStr + " " + tmp2.tmpStr)
   }
}

1. 结果为第一名"

如果我的代码像这样调用一个.environmentObject()

And if my code calls one .environmentObject() like

TestView().environmentObject(TempStr(initStr: "1st")) 

来自TestView的

tmp1和tmp2都具有相同的值 TempStr(initStr:"1st").看起来 .environmentObject()调用设置了所有相同类型的值.

both tmp1 and tmp2 from TestView have same value TempStr(initStr: "1st"). it looks like .environmentObject() call sets all values of same type.

实际上，我知道这是行不通的，但我只是尝试使用此问题进行尝试.

Actually, I knew that it couldn't work but I just tried it for using this question.

我想知道实现我的目标的正确方法是什么.

I wonder what is correct way of achieving my goal.

谢谢

推荐答案

这有效:

场景代理:

class MyModel: ObservableObject {
    @Published var tmpStr1:TempStr!
    @Published var tmpStr2:TempStr!

    init(initStr1: String, initStr2:String) {
        tmpStr1 = TempStr(initStr: initStr1)
        tmpStr2 = TempStr(initStr: initStr2)
    }
}
class TempStr: ObservableObject {
    @Published var tmpStr:String!

    init(initStr: String) {
        tmpStr = initStr
    }
}

ContentView:

struct ContentView: View {
    @EnvironmentObject var myModel: MyModel
    var body: some View {
        Text(myModel.tmpStr1.tmpStr + " " + myModel.tmpStr2.tmpStr)
    }
}

当然，这可能不是您想要的，但这引出了一个问题-为什么想要两个 class 实例，而又不想在模型中?您可以轻松地拥有两个 separate 类作为模型的模型(以及 ObservableObjects )，并且如果您希望每个 SceneDelegate 有两个单独的模型实例?在那里.

Granted, this may not be what you are looking for, but that begs the question - why do want want two instances of a class without wanting each in your model? You can easily have two separate classes as pat of your model (and as ObservableObjects) and if you want two separate instances of your model per SceneDelegate? There it is.

但是，如果您想要模型/类/任何对象的两个实例，则感觉像是重构的候选对象.

But if you want two instances of your model/class/whatever, it feels like a candidate for refactoring.

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