Swiftui：是否可以将观察者视为环境对象？

发布于 2025-01-28 08:48:16 字数 1592 浏览 4 评论 0原文

如果我使用@publed属性创建一个observableObject，并将其注入Swifui视图中，则使用.environMentObject（），该视图响应于变化可观察的对象如预期的。

class CounterStore: ObservableObject {
    @Published private(set) var counter = 0
    func increment() {
        counter += 1
    }
}

struct ContentView: View {
    @EnvironmentObject var store: CounterStore

    var body: some View {
        VStack {
            Text("Count: \(store.counter)")
            Button(action: { store.increment() }) {
                Text("Increment")
            }
        }
    }
}

点击“增量”将增加计数。

但是，如果我不使用EnvironmentObject，而是将商店实例传递到视图中，则编译器不抱怨，商店方法engrement（）在按钮被轻拍，但view中的计数不是更新。

struct ContentViewWithStoreAsParameter: View {
    var store: CounterStore

    var body: some View {
        VStack {
            Text("Count: \(store.counter) (DOES NOT UPDATE)")
            Button(action: { store.increment() }) {
                Text("Increment")
            }
        }
    }
}

这是我调用这两种视图的方式：

@main
struct testApp: App {
    var store = CounterStore()
    
    var body: some Scene {
        WindowGroup {
            VStack {
                ContentView().environmentObject(store) // works
                ContentViewWithStoreAsParameter(store: store) // broken
            }
        }
    }
}

有没有办法将observableObject作为参数作为参数？（或什么魔术是.environmentalObject（）在幕后做什么？

原文

If I create an ObservableObject with a @Published property and inject it into a SwifUI view with .environmentObject(), the view responds to changes in the ObservableObject as expected.

class CounterStore: ObservableObject {
    @Published private(set) var counter = 0
    func increment() {
        counter += 1
    }
}

struct ContentView: View {
    @EnvironmentObject var store: CounterStore

    var body: some View {
        VStack {
            Text("Count: \(store.counter)")
            Button(action: { store.increment() }) {
                Text("Increment")
            }
        }
    }
}

Tapping on "Increment" will increase the count.

However, if I don't use the EnvironmentObject and instead pass the store instance into the view, the compiler does not complain, the store method increment() is called when the button is tapped, but the count in the View does not update.

struct ContentViewWithStoreAsParameter: View {
    var store: CounterStore

    var body: some View {
        VStack {
            Text("Count: \(store.counter) (DOES NOT UPDATE)")
            Button(action: { store.increment() }) {
                Text("Increment")
            }
        }
    }
}

Here's how I'm calling both Views:

@main
struct testApp: App {
    var store = CounterStore()
    
    var body: some Scene {
        WindowGroup {
            VStack {
                ContentView().environmentObject(store) // works
                ContentViewWithStoreAsParameter(store: store) // broken
            }
        }
    }
}

Is there a way to pass an ObservableObject into a View as a parameter? (Or what magic is .environmentalObject() doing behind the scenes?)

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放飞的风筝 2025-02-04 08:48:16

应该以某种方式观察到

struct ContentViewWithStoreAsParameter: View {
    @ObservedObject var store: CounterStore
//...

It should be observed somehow, so next works

struct ContentViewWithStoreAsParameter: View {
    @ObservedObject var store: CounterStore
//...

回复收藏 0 原文

硬不硬你别怂 2025-02-04 08:48:16

您可以轻松地以@StateObject>：

@main
struct testApp: App {
    @StateObject var store = CounterStore()
    
    var body: some Scene {
        WindowGroup {
            VStack {
                ContentView().environmentObject(store) // works
                ContentViewWithStoreAsParameter(store: store) // also works
            }
        }
    }
}

struct ContentViewWithStoreAsParameter: View {
    @StateObject var store: CounterStore

    var body: some View {
        VStack {
            Text("Count: \(store.counter)") // now it does update
            Button(action: { store.increment() }) {
                Text("Increment")
            }
        }
    }
}

但是，商店通常仅适用于需要它的视图，为什么此解决方案在此上下文中最有意义：

struct ContentView: View {
    @StateObject var store = CounterStore()

    var body: some View {
        VStack {
            Text("Count: \(store.counter)")
            Button(action: { store.increment() }) {
                Text("Increment")
            }
        }
    }
}

You can pass down your store easily as @StateObject:

@main
struct testApp: App {
    @StateObject var store = CounterStore()
    
    var body: some Scene {
        WindowGroup {
            VStack {
                ContentView().environmentObject(store) // works
                ContentViewWithStoreAsParameter(store: store) // also works
            }
        }
    }
}

struct ContentViewWithStoreAsParameter: View {
    @StateObject var store: CounterStore

    var body: some View {
        VStack {
            Text("Count: \(store.counter)") // now it does update
            Button(action: { store.increment() }) {
                Text("Increment")
            }
        }
    }
}

However, the store should normally only be available for the views that need it, why this solution would make the most sense in this context:

struct ContentView: View {
    @StateObject var store = CounterStore()

    var body: some View {
        VStack {
            Text("Count: \(store.counter)")
            Button(action: { store.increment() }) {
                Text("Increment")
            }
        }
    }
}

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