如何检测没有移动或持续时间的SwiftUI touchDown事件? [英] How do you detect a SwiftUI touchDown event with no movement or duration?
问题描述
我正在尝试检测手指何时首次与SwiftUI中的视图进行接触.我可以使用UIKit Events非常轻松地做到这一点,但是无法在SwiftUI中解决这个问题.
I'm trying to detect when a finger first makes contact with a view in SwiftUI. I could do this very easily with UIKit Events but can't figure this out in SwiftUI.
我尝试了最小移动为0的DragGesture,但直到您的手指移动它仍然不会改变.
I've tried a DragGesture with minimum movement of 0 but it still won't change until your finger moves.
TapGesture仅在您松开手指时起作用,而无论我将参数设置为什么,LongPressGesture都不会足够快地触发.
TapGesture will only work when you lift your finger and LongPressGesture will not trigger fast enough no matter what I set the parameters to.
DragGesture(minimumDistance: 0, coordinateSpace: .local).onChanged({ _ in print("down")})
LongPressGesture(minimumDuration: 0.01, maximumDistance: 100).onEnded({_ in print("down")})
我想在手指与视图接触时立即检测到touchDown事件. Apple的默认手势对距离或时间有限制.
I want to detect a touchDown event as soon as a finger makes contact with a view. Apple's default gestures have restrictions to either distance or time.
更新:这不再是问题,因为苹果似乎已经更新了DragGesture的工作方式,或者我遇到了特定的上下文错误.
Update: This is not an issue anymore as Apple has seemed to update how DragGesture works or maybe I was experiencing a specific contextual bug.
推荐答案
如果将以下两个问题中的代码组合在一起:
If you combine the code from these two questions:
UITapGestureRecognizer-使它在触地而不是触地时起作用吗?
您可以进行以下操作:
ZStack {
Text("Test")
TapView {
print("Tapped")
}
}
struct TapView: UIViewRepresentable {
var tappedCallback: (() -> Void)
func makeUIView(context: UIViewRepresentableContext<TapView>) -> TapView.UIViewType {
let v = UIView(frame: .zero)
let gesture = SingleTouchDownGestureRecognizer(target: context.coordinator,
action: #selector(Coordinator.tapped))
v.addGestureRecognizer(gesture)
return v
}
class Coordinator: NSObject {
var tappedCallback: (() -> Void)
init(tappedCallback: @escaping (() -> Void)) {
self.tappedCallback = tappedCallback
}
@objc func tapped(gesture:UITapGestureRecognizer) {
self.tappedCallback()
}
}
func makeCoordinator() -> TapView.Coordinator {
return Coordinator(tappedCallback:self.tappedCallback)
}
func updateUIView(_ uiView: UIView,
context: UIViewRepresentableContext<TapView>) {
}
}
class SingleTouchDownGestureRecognizer: UIGestureRecognizer {
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
if self.state == .possible {
self.state = .recognized
}
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
self.state = .failed
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent) {
self.state = .failed
}
}
我们肯定可以做出一些抽象,以便其用法更像其他SwiftUI手势,但这只是一个开始.希望苹果在某个时候能够对此提供支持.
There's definitely some abstractions we can make so that the usage is more like the other SwiftUI Gestures, but this is a start. Hopefully Apple builds in support for this at some point.
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