【发布时间】：2021-10-13 14:07:09
【问题描述】：
我目前正在尝试编写一个导航类似于 Affinity 或 Procreate 等应用的应用，您可以在其中使用单点触摸/拖动来绘制、润饰和交互，以及两指在画布上导航的手势。
我正在使用 SwiftUI 作为主要框架并根据需要包含 UIKit 来构建应用程序。
不幸的是，SwiftUI 还不允许像描述的那样复杂的手势，但 UIKit 通常可以。所以我恢复使用 UIKit 作为我的手势识别器，而不是依赖 SwiftUI 手势。然而，这导致了问题，即只会调用最顶层的手势识别器。 我希望同时识别多个手势 like demonstrated here，但不幸的是，SwiftUI 似乎会导致 UIViewRepresentables 出现问题。
有人可以帮我找出解决办法吗？
重要提示：我正在使用两个单独的视图来执行此操作，因为从长远来看，它们将用于不同的视图。但是，在示例中，出于演示目的，我将它们放在同一个视图中。
用法：
ZStack {
DragGestureView { point in
print("One Finger")
} dragEndedCallback: {
print("One Finger Ended")
}
TwoFingerNavigationView { point in
viewStore.send(.dragChanged(point))
print("Two Fingers")
} dragEndedCallback: {
viewStore.send(.dragEnded)
print("Two Fingers Ended")
} pinchedCallback: { value in
viewStore.send(.magnificationChanged(value))
} pinchEndedCallback: {
viewStore.send(.magnificationEnded)
}
content()
.position(viewStore.location)
.scaleEffect(viewStore.scale * viewStore.offsetScale)
}
DragGestureView
public struct DragGestureView: UIViewRepresentable {
let delegate = GestureRecognizerDelegate()
var draggedCallback: ((CGPoint) -> Void)
var dragEndedCallback: (() -> Void)
public init(draggedCallback: @escaping ((CGPoint) -> Void), dragEndedCallback: @escaping (() -> Void)) {
self.draggedCallback = draggedCallback
self.dragEndedCallback = dragEndedCallback
}
public class Coordinator: NSObject {
var draggedCallback: ((CGPoint) -> Void)
var dragEndedCallback: (() -> Void)
public init(draggedCallback: @escaping ((CGPoint) -> Void),
dragEndedCallback: @escaping (() -> Void)) {
self.draggedCallback = draggedCallback
self.dragEndedCallback = dragEndedCallback
}
@objc func dragged(gesture: UIPanGestureRecognizer) {
if gesture.state == .ended {
self.dragEndedCallback()
} else {
self.draggedCallback(gesture.location(in: gesture.view))
}
}
}
class GestureRecognizerDelegate: NSObject, UIGestureRecognizerDelegate {
func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
return true
}
}
public func makeUIView(context: UIViewRepresentableContext<DragGestureView>) -> DragGestureView.UIViewType {
let view = UIView(frame: .zero)
let gesture = UIPanGestureRecognizer(target: context.coordinator,
action: #selector(Coordinator.dragged))
gesture.minimumNumberOfTouches = 1
gesture.maximumNumberOfTouches = 1
gesture.delegate = delegate
view.addGestureRecognizer(gesture)
return view
}
public func makeCoordinator() -> DragGestureView.Coordinator {
return Coordinator(draggedCallback: self.draggedCallback,
dragEndedCallback: self.dragEndedCallback)
}
public func updateUIView(_ uiView: UIView,
context: UIViewRepresentableContext<DragGestureView>) {
}
}
TwoFingerNavigationView
struct TwoFingerNavigationView: UIViewRepresentable {
let delegate = GestureRecognizerDelegate()
var draggedCallback: ((CGPoint) -> Void)
var dragEndedCallback: (() -> Void)
var pinchedCallback: ((CGFloat) -> Void)
var pinchEndedCallback: (() -> Void)
class Coordinator: NSObject {
var draggedCallback: ((CGPoint) -> Void)
var dragEndedCallback: (() -> Void)
var pinchedCallback: ((CGFloat) -> Void)
var pinchEndedCallback: (() -> Void)
var startingDistance: CGFloat? = nil
var isMagnifying = false
var startingMagnification: CGFloat? = nil
var newMagnification: CGFloat = 1.0
init(draggedCallback: @escaping ((CGPoint) -> Void),
dragEndedCallback: @escaping (() -> Void),
pinchedCallback: @escaping ((CGFloat) -> Void),
pinchEndedCallback: @escaping (() -> Void)) {
self.draggedCallback = draggedCallback
self.dragEndedCallback = dragEndedCallback
self.pinchedCallback = pinchedCallback
self.pinchEndedCallback = pinchEndedCallback
}
@objc func dragged(gesture: UIPanGestureRecognizer) {
if gesture.state == .ended {
self.dragEndedCallback()
self.pinchEndedCallback()
startingDistance = nil
isMagnifying = false
startingMagnification = nil
newMagnification = 1.0
} else {
self.draggedCallback(gesture.translation(in: gesture.view) / (newMagnification))
}
var touchLocations: [CGPoint] = []
for i in 0..<gesture.numberOfTouches{
touchLocations.append(gesture.location(ofTouch: i, in: gesture.view))
}
if touchLocations.count == 2 {
let distanceVector = (touchLocations[0] - touchLocations[1])
let distance = sqrt(distanceVector.x * distanceVector.x + distanceVector.y * distanceVector.y)
guard startingDistance != nil else { startingDistance = distance; return }
guard distance - startingDistance! > 30 || distance - startingDistance! < -30 || isMagnifying else { return }
isMagnifying = true;
if startingMagnification == nil {
startingMagnification = distance / 100
pinchedCallback(1)
} else {
let magnification = distance / 100
newMagnification = magnification / startingMagnification!
pinchedCallback(newMagnification)
}
}
}
}
class GestureRecognizerDelegate: NSObject, UIGestureRecognizerDelegate {
func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
return true
}
}
func makeUIView(context: UIViewRepresentableContext<TwoFingerNavigationView>) -> TwoFingerNavigationView.UIViewType {
let view = UIView(frame: .zero)
let gesture = UIPanGestureRecognizer(target: context.coordinator,
action: #selector(Coordinator.dragged))
gesture.minimumNumberOfTouches = 2
gesture.maximumNumberOfTouches = 2
gesture.delegate = delegate
view.addGestureRecognizer(gesture)
return view
}
func makeCoordinator() -> TwoFingerNavigationView.Coordinator {
return Coordinator(draggedCallback: self.draggedCallback,
dragEndedCallback: self.dragEndedCallback,
pinchedCallback: self.pinchedCallback,
pinchEndedCallback: self.pinchEndedCallback)
}
func updateUIView(_ uiView: UIView,
context: UIViewRepresentableContext<TwoFingerNavigationView>) {
}
}
【问题讨论】：
-
你很幸运——你可以简单地将两个手势识别器放到一个实现 UIViewRepresentable 的类中。它适用于我的自定义手势识别器和标准 UITapGestureRecognizer。就我而言，我需要 SwiftUI 按钮才能与 UIKit 手势识别器一起使用，并且当我添加带有使用自定义 UIGestureRecognizer 的自定义视图的背景时，所有按钮都会停止工作（以及其他 SwiftUI 控件）。
标签： ios swiftui uikit uigesturerecognizer