Detect UILongPressGestureRecognizer direction not compare initial point - ios

Question

if (gesture.state == UIGestureRecognizerStateBegan) {
_initial = [gesture locationInView:self.view];
}else if (gesture.state == UIGestureRecognizerStateChanged){
CGPoint p = [gesture locationInView:self.view];
double dy = p.y - _initial.y;
if (dy > 0) {
NSLog(#"Finger moved to the up");
}
else {
NSLog(#"Finger moved to the down");
}
}
This is my method to detect UILongPressGestureRecognizer direction, but I want
detect direction not compare initial point but compare stateChanged point.
It's hard to describe, like : form 0 to 7 is up, but 7 to -5 is down and then -5 to -2 is up.

Answer 1

You should use translationInView.
CGPoint translation = [gesture translationInView:view.superview];
if (translation.y>0) {
// moving up
} else {
// moving down
}

Answer 2

A friend of mine give me some advice and it works well:
CGPoint point = [gestureRecognizer locationInView:self.view];
if(gestureRecognizer.state == UIGestureRecognizerStateBegan){
_lastY = point.y;
}else if(gestureRecognizer.state == UIGestureRecognizerStateChanged) {
double y = point.y - _lastY;
if (y < 0.f) {
NSLog(#"****up*****");
}else{
NSLog(#"****down*****");
}
_lastY = point.y;
}
I know it's not a good one but it works, any idea?

Answer 3

Swift 3
Here's a complete function to determine left or right movement of UILongPressGestureRecognizer:
#objc func swipePress (_ sender: UILongPressGestureRecognizer) {
let location = sender.location(in: self.view)
print ("Location : \(location.x)")
if sender.state == .ended {
print("swipe ended")
buttonCreated = false
animateRemoveArrows()
if gestureDirection == "right" {
print("going forward")
if myWebView.canGoForward {
myWebView.goForward() //go forward
} else {
}
} else if gestureDirection == "left" {
print("going backward")
if myWebView.canGoBack {
myWebView.goBack() //go back
} else {
}
} else {
}
} else if sender.state == .began {
gestureDirection = "" // reset direction
print("swipe started")
firstPoisitionX = location.x
firstPoisitionY = location.y
print ("Last x: \(firstPoisitionX)")
} else if sender.state == .changed {
if location.y > (firstPoisitionY + 100) {
print("going up or down")
} else if location.y < (firstPoisitionY - 100) {
print("going up or down")
} else if location.x > (firstPoisitionX + 50) {
print("going right")
if buttonCreated == false { // only create one button
showArrow(direction: "right")
print(rightArrow.center)
gestureDirection = "right"
buttonCreated = true
}
} else if location.x < (firstPoisitionX - 50) {
print("going left")
if buttonCreated == false { // only create one button
showArrow(direction: "left")
print(leftArrow.center)
gestureDirection = "left"
buttonCreated = true
}
}
}
}