UISwipeGestureRecognizer Swipe length - iphone

Question

Any idea if there is a way to get the length of a swipe gesture or the touches so that i can calculate the distance?

Answer 1

It's impossible to get a distance from a swipe gesture, because the SwipeGesture triggers the method where you could access the location exactly one time, when the gesture has ended.
Maybe you want to use a UIPanGestureRecognizer.
If it possible for you to use pan gesture you would save the starting point of the pan, and if the pan has ended calculate the distance.
- (void)panGesture:(UIPanGestureRecognizer *)sender {
if (sender.state == UIGestureRecognizerStateBegan) {
startLocation = [sender locationInView:self.view];
}
else if (sender.state == UIGestureRecognizerStateEnded) {
CGPoint stopLocation = [sender locationInView:self.view];
CGFloat dx = stopLocation.x - startLocation.x;
CGFloat dy = stopLocation.y - startLocation.y;
CGFloat distance = sqrt(dx*dx + dy*dy );
NSLog(#"Distance: %f", distance);
}
}

Answer 2

In Swift
override func viewDidLoad() {
super.viewDidLoad()
// add your pan recognizer to your desired view
let panRecognizer = UIPanGestureRecognizer(target: self, action: #selector(panedView))
self.view.addGestureRecognizer(panRecognizer)
}
#objc func panedView(sender:UIPanGestureRecognizer){
var startLocation = CGPoint()
//UIGestureRecognizerState has been renamed to UIGestureRecognizer.State in Swift 4
if (sender.state == UIGestureRecognizer.State.began) {
startLocation = sender.location(in: self.view)
}
else if (sender.state == UIGestureRecognizer.State.ended) {
let stopLocation = sender.location(in: self.view)
let dx = stopLocation.x - startLocation.x;
let dy = stopLocation.y - startLocation.y;
let distance = sqrt(dx*dx + dy*dy );
NSLog("Distance: %f", distance);
if distance > 400 {
//do what you want to do
}
}
}
Hope that helps all you Swift pioneers

Answer 3

func swipeAction(gesture: UIPanGestureRecognizer) {
let transition = sqrt(pow(gesture.translation(in: view).x, 2)
+ pow(gesture.translation(in: view).y, 2))
}

Answer 4

For those of us using Xamarin:
void panGesture(UIPanGestureRecognizer gestureRecognizer) {
if (gestureRecognizer.State == UIGestureRecognizerState.Began) {
startLocation = gestureRecognizer.TranslationInView (view)
} else if (gestureRecognizer.State == UIGestureRecognizerState.Ended) {
PointF stopLocation = gestureRecognizer.TranslationInView (view);
float dX = stopLocation.X - startLocation.X;
float dY = stopLocation.Y - startLocation.Y;
float distance = Math.Sqrt(dX * dX + dY * dY);
System.Console.WriteLine("Distance: {0}", distance);
}
}

Answer 5

You can only do it a standard way: remember the touch point of touchBegin and compare the point from touchEnd.

Answer 6

I have an implementation similar to the answer in swift that discriminates between a drag and a swipe calculating the distance relative to the container and the speed of the swipe.
#objc private func handleSwipe(sender: UIPanGestureRecognizer) {
if (sender.state == .began) {
self.swipeStart.location = sender.location(in: self)
self.swipeStart.time = Date()
}
else if (sender.state == .ended) {
let swipeStopLocation : CGPoint = sender.location(in: self)
let dx : CGFloat = swipeStopLocation.x - swipeStart.location.x
let dy : CGFloat = swipeStopLocation.y - swipeStart.location.y
let distance : CGFloat = sqrt(dx*dx + dy*dy );
let speed : CGFloat = distance / CGFloat(Date().timeIntervalSince(self.swipeStart.time))
let portraitWidth = min(self.frame.size.width, self.frame.size.height)
print("Distance: \(distance), speed: \(speed), dy: \(dy), dx: \(dx), portraitWidth: \(portraitWidth), c1: \(distance > portraitWidth * 0.4), c2: \(abs(dy) < abs(dx) * 0.25), c3: \(speed > portraitWidth * 3.0) ")
if distance > portraitWidth * 0.4 && abs(dy) < abs(dx) * 0.25 && speed > portraitWidth * 3.0 {
if dx > 0 {
delegate?.previousAssetPressed(self)
}else{
delegate?.nextAssetPressed(self)
}
}
}
}