[英]SwiftUI drag gesture freezes with multi-touch
I am trying to drag a view in SwiftUI.我正在尝试在 SwiftUI 中拖动视图。
The drag works perfectly until I place my second finger on screen, after that the drag stops and neither of the code blocks ( onChanged
, onEnded
) gets called.拖动效果很好,直到我将第二根手指放在屏幕上,之后拖动停止并且代码块(
onChanged
, onEnded
)都不会被调用。
But, when I again start dragging with a single finger, it again starts working.但是,当我再次开始用单指拖动时,它又开始工作了。
Is there any work around to fix this or I am missing something?有什么办法可以解决这个问题还是我遗漏了什么?
struct Pager: View {
func drag(geometry: GeometryProxy) -> some Gesture {
DragGesture()
.onChanged({ (value) in
//some code
})
.onEnded({ (value) in
//some code
})
}
var body: some View {
GeometryReader { (geometry) in
ZStack {
ForEach(self.items.indices.reversed(), id: \.self) { index in
Card(index: index, item: self.items[index])
.offset(x: 0, y: self.offset(index: index, geometry: geometry))
.animation(.linear)
}
}
.background(Color.black)
.gesture(self.drag(geometry: geometry))
}
}
}
You can use the same solution as this post , as I believe it is the same underlying problem.您可以使用与这篇文章相同的解决方案,因为我相信这是相同的潜在问题。 The solution employs a GestureState, which (as stated in the linked post) is a temporary value, and returns back to its initial state (0, 0) when the gesture is completed/interrupted.
该解决方案使用 GestureState,它(如链接帖子中所述)是一个临时值,并在手势完成/中断时返回到其初始 state (0, 0)。
Your code should look something like this when using the GestureState (though you may be able to adapt it to use a separate drag method like in your original post):使用 GestureState 时,您的代码应如下所示(尽管您可以对其进行调整以使用单独的拖动方法,如原始帖子中所示):
struct Pager: View {
@GestureState private var dragPosition = CGSize.zero
var body: some View {
ZStack {
ForEach(self.items.indices.reversed(), id: \.self) { index in
Card(index: index, item: self.items[index])
.offset(x: 0, y: self.dragPosition.height) // This will now map the y offset of the card to the dragPosition GestureState. If you want the x offset use self.dragPosition.width
.animation(.linear)
}
}
.background(Color.black)
.gesture(
DragGesture()
.updating($dragPosition) { (value, gestureState, transaction) in
gestureState = CGSize(width: value.location.x - value.startLocation.x, height: value.location.y - value.startLocation.y)
}
.onChanged { value in
print("I'm changing")
}
.onEnded { value in
print("I've ended")
}
)
}
}
This approach is pretty helpful:这种方法非常有用:
Detect DragGesture cancelation in SwiftUI 检测 SwiftUI 中的 DragGesture 取消
So basically, you compose the drag gesture with pinch & rotation gestures(combine them using.simultaneously).所以基本上,你用捏合和旋转手势组成拖动手势(使用.simultaneously 组合它们)。
When either pinch or rotation gets triggered, you can use it to signal a cancellation for your drag gesture and update your state accordingly当触发捏合或旋转时,您可以使用它来发出取消拖动手势的信号并相应地更新您的 state
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