SwiftUI：Gesture var 是不是可能移入 EnvironmentObject？

Posted 2023-02-24

【中文标题】SwiftUI：Gesture var 是不是可能移入 EnvironmentObject？

【英文标题】：SwiftUI: is possible Gesture var move into EnvironmentObject?SwiftUI：Gesture var 是否可能移入 EnvironmentObject？

【发布时间】：2021-10-22 10:18:24

【问题描述】：

我不熟悉 SWIFTUI 和闭包。这里将一些手势代码移动到扩展功能，除了 var drag。 对于手势，是否可以将拖动移动到 environmentObject 中？如何初始化？

class ViewState:ObservableObject 
    @Published  var isDragging = false
    @Published  var size: CGFloat = 100.0


struct ContentView: View 
    @StateObject var  viewState:ViewState=ViewState()

    var drag:some Gesture  isDrag(viewState) 

    var body: some View 
       Circle()
           .fill(viewState.isDragging ? Color.red: Color.blue)
           .frame(width:viewState.size, height:viewState.size, alignment: .center)
            .gesture(drag)
        
     



extension ContentView 
    func isDrag(_ viewState:ViewState)->some Gesture 
          DragGesture()
             .onChanged _ in
                viewState.isDragging = true
                viewState.size += 10.0
             
             .onEnded_ in
                viewState.isDragging = false
                viewState.size = 100.0
            
         
     

【参考方案1】：

完成，闭包就是函数！现在，我可以将此代码移动到其他视图，但仍会更新视图风险。并且声明的数据（environmentObject）不是独立的。

class ViewState:ObservableObject 
    @Published  var isDragging = false
    @Published  var size: CGFloat = 100.0

struct ContentView: View 
    @StateObject var  viewState:ViewState=ViewState()

   // var drag:some Gesture  

    var body: some View 
       Circle()
           .fill(viewState.isDragging ? Color.red: Color.blue)
           .frame(width:viewState.size, height:viewState.size, alignment: .center)
           .isDragged(viewState)
        
     



extension View 
    func drag(_ viewState:ViewState)->some Gesture 
          DragGesture()
             .onChanged _ in
                viewState.isDragging = true
                viewState.size += 10.0
             
             .onEnded_ in
                viewState.isDragging = false
                viewState.size = 100.0
            
         
     

    @ViewBuilder func isDragged(_ viewState:ViewState) -> some View 
        self.gesture(drag(viewState))