swift - 在安装在 View 之外访问 State 的值。这将导致初始值的恒定绑定，并且不会更新

Question

我试图将手势封装在一个类中，然后在另一个视图中调用它。我的项目可以运行良好，也可以构建良好。但是 Xcode12 给了我一个粉红色的错误。这是我的代码

class GestureClass: ObservableObject {
    private var minZoom:CGFloat=1
    private var maxZoom:CGFloat=4.00
    
    @GestureState private var magnificationLevel:CGFloat=1
    @Published public var zoomLevel:CGFloat=1
    @Published public var current:CGFloat=1
    
    var magnify: some Gesture {
        MagnificationGesture()
        .updating($magnificationLevel, body:{(value,state,_) in
           return state=value
        })
        .onChanged({ value in
            self.current = value
        })
        .onEnded({ value in
            self.zoomLevel = self.setZoom(value)
            self.current = 1
        })
    }
       
    func setZoom(_ gesturevalue:CGFloat) -> CGFloat {
        return max(min(self.zoomLevel*gesturevalue, self.maxZoom), self.minZoom)
    }
    
    func gestureresult() -> CGFloat {
        return self.setZoom(self.current)
    }
}

struct GestureModelView: View {
    @EnvironmentObject var gesturemodel:GestureClass
    var body: some View {
        let myges = gesturemodel.magnify
        
        HStack {
            Rectangle()
                .foregroundColor(.blue)
                .frame(width:200*gesturemodel.gestureresult(), height:200)
                .gesture(myges)
        }
    }
}

Answer 1

我在计算属性中删除了这段代码，错误消失了。但我真的不知道为什么。</p>

.updating($magnificationLevel, body:{(value,state,_) in
           return state=value
        })