recognizing long press gesture in spriteKit - ios

Hi I am currently moving a sprite by checking if the button was pressed in touchesBegan and then updating the position in update. I am doing this so that the user does not need to keep pressing the move up/down/left/right etc button over and over. The problem is that sometimes the sprite does not stop moving which im sure is due to this. Does anyone know a better solution to this? For brevity I will show you the way I am taking care of the up button.
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
for touch: AnyObject in touches {
// Get the location of the touch in this scene
let location = touch.locationInNode(self)
// Check if the location of the touch is within the button's bounds
if upButton.containsPoint(location) {
upButtonPressed = true
}
override func update(currentTime: CFTimeInterval) {
if upButtonPressed == true {
ball.position.y += 3
}
I kept it simple here but I do have all the conditions to stop movement in my code. I am simply wondering if there is an easier way to do this with maybe a long press gesture recognizer?

Related

Defining my spaceship movement in spritekit game in Swift

Hi I am new to Xcode and Swift, right now I am trying to design a game that involves a spaceship as player with alien spaceships.
I ran into a little problem where I am trying to differentiate the movement of the spaceship from the firing of the spaceship.
Basically I used touchesBegan() function to run the function which my spaceship fires, and touchesMoved() function to move the spaceship's x-position.
These are the code:
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
pShoot()
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches{
let location = touch.location(in: self)
spaceship.run(SKAction.moveTo(x: location.x, duration: 0.5))
}
}
What I am trying to do is to differentiate the clicking or touching indicator and pressed and move indicator, in other words I dont want the spaceship to fire when I am pressed and move on the screen, and I do not want the spaceship to move when I am clicking constantly but at different position. ( touchesMoved() detects changes in touch positions so if I am clicking at different positions spaceship will move which I dont want)
I would like to know what would be the best way of implementing this, thank you.
You could try checking the area that the user pressed and deciding whether or not to move the spaceship depending on the origin of the touch.

UIButton touchDragEnter and touchDragExit called too often

How can I avoid a UIButtons .touchDragEnter and .touchDragExit functions from rapid firing? This question demonstrates the issue perfectly, but the only answer does not describe how to work around it. I'm trying to animate a button when the users finger on the button, and animate it again when their finger slides off. Are there any better ways to do this? If not, how should I stop my animation code from firing multiple times when the users finger is right between an .enter and an .exit state?
You could instead track the location of the touch point itself and determine when the touch point moves in and out of the button
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
if let touch = touches.first {
let point = t.location(in: self)
// moving in to the button
if button.frame.contains(point) && !wasInButton {
// trigger animation
wasInButton = true
}
// moving out of the button
if !button.frame.contains(point) && wasInButton {
// trigger animation
wasInButton = false
}
}
}
wasInButton could be a boolean variable set to true when there is a touch down in the button's frame:
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
if let touch = touches.first {
let point = t.location(in: self)
if button.frame.contains(point) {
wasInButton = true
// trigger animation
} else {
wasInButton = false
}
}
This would require you to subclass the button's superview. And since you might not want to animate as soon as the point leaves the button's frame (because the user's finger or thumb would still be covering most of the button), you could instead do the hit test in a larger frame that encapsulates your button.

Swift Gesture Recognizer That Tracks Only First Touch In Continuous Gesture

I'm trying to use a gesture recognizer to allow the user to resize a view on the screen by dragging it with one finger... as such, I want to track all changes to the touch. I initially tried to use a PanGestureRecognizer for this, but I've run into an issue when the user touches the view with multiple fingers. I only want to track the first touch (ie the first finger the user places on the screen during a gesture), but I can't find a way to prevent additional touches from interfering with my ability to track the first. My initial solution was to simply set
recognizer.maximumNumberOfTouches = 1
However, this causes the entire gesture to be cancelled in the event of a second touch (I want to continue tracking the first touch in this case). But, of course, not setting this value to 1 causes the gesture to actually track multiple touches. How can I make a gesture recognizer that tracks all changes to only the first touch in the gesture, and isn't cancelled by additional touches on the screen?
From your comments and answer, it sounds like your use of a pan gesture recognizer was always wrong and you were doing something wrong in your action handler. No correct action handler for a pan gesture recognizer would ever use location(in:) for anything. location(in:) gives you a centroid of all touches, which is exactly what you say you don't want — and in any case there is no need to consult it.
If your goal is to drag a view, you use translation(in:).
If your goal is to track the actual location of a particular touch, you use location(ofTouch:in:).
If you discover that a touch is being delivered and you don't want it tracked, call ignore(_:for:).
Here is a UIGestureRecognizer subclass that will track all changes the first touch the user places on the screen at the start of a gesture, and will ignore all other fingers without cancelling the gesture. Note that if you're using functions/properties of the gesture recognizer (such as location(in:)), you'll probably have to override those as well.
class FirstTouchGestureRecognizer: UIGestureRecognizer {
private var firstTouch: UITouch? = nil
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
if firstTouch == nil {
firstTouch = touches.first!
self.state = .began
}
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
if firstTouch != nil && touches.contains(firstTouch!) {
self.state = .changed
}
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent) {
if firstTouch != nil && touches.contains(firstTouch!) {
firstTouch = nil
self.state = .ended
}
}
}

How to replicate iOS home screen behaviour?

I am currently working on a game in SpriteKit, where I need to move a sprite in response to touch (i.e when user swipes or pans anywhere in SKView.
I want to get the direction of pan (for swipe I know how to do it),so that the sprite will move according to pan (I have a path defined for the sprite if user pans or according to swipe if user swipes), the way touch in iOS appdrawer works i.e it responds to slightest of swipes and also pans (i.e when you pan forwards or backwards, it makes a decision whether you want to move to the next screen or not).
Is there any documentation or so? (I have gone through the UIGestureRecognizer documentation, but I haven't been able to find a way to implement it.)
I use something similar on my MenuScene, I have 3 pages setup that the user can scroll through to get various game data. But I don't want the slightest touch to move the screen, it would be to jarring for the user. So I just watch the finger movements in the Touches functions and check if the movement is greater that an amount I designate as the minimum move amount and if it is greater than I scroll the page. In your case you could handle it as; if it is greater than the minimum move amount treat as a pan else treat it as a swipe
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
let touch: UITouch = touches.first!
initialTouch = touch.location(in: self.view!)
moveAmtY = 0
moveAmtX = 0
initialPosition = menuScroller.position
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
let touch: UITouch = touches.first!
let movingPoint: CGPoint = touch.location(in: self.view!)
moveAmtX = movingPoint.x - initialTouch.x
moveAmtY = movingPoint.y - initialTouch.y
//their finger is on the page and is moving around just move the scroller and parallax backgrounds around with them
//Check if it needs to scroll to the next page when they release their finger
menuScroller.position = CGPoint(x: initialPosition.x + moveAmtX, y: initialPosition.y)
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
//they havent moved far enough so just reset the page to the original position
if fabs(moveAmtX) > 0 && fabs(moveAmtX) < minimum_detect_distance {
resetPages()
}
//the user has swiped past the designated distance, so assume that they want the page to scroll
if moveAmtX < -minimum_detect_distance {
moveLeft()
}
else if moveAmtX > minimum_detect_distance {
moveRight()
}
}

iOS UIPanGestureRecognizer: adjust sensitivity?

My question: Is there a way to adjust the "sensitivity" of UIPanGestureRecognizer so that it turns on 'sooner', i.e. after moving a fewer number of 'pixels'?
I have a simple app with a UIImageView, and pinch and pan gesture recognizers tied to this so that the user can zoom in and draw on the image by hand. Works fine.
However, I notice the stock UIPanGestureRecognizer doesn't return a value of UIGestureRecognizerState.Changed until the user's gesture has moved about 10 pixels.
Example: Here's a screenshot showing several lines that I've attempted to draw shorter & shorter, and there is a noticeable finite length below which no line gets drawn because the pan gesture recognizer never changes state.
IllustrationOfProgressivelyShorterLines.png
...i.e., to the right of the yellow line, I was still trying to draw, and my touches were being recognized as touchesMoved events, but the UIPanGestureRecognizer wasn't firing its own "Moved" event and thus nothing was getting drawn.
(Note/clarification: That image takes up the entirety of my iPad's screen, so my finger is physically moving more than an inch even in the cases where no state change occurs to the recognizer. It's just that we're 'zoomed in' in terms of the tranformation generated by the pinch gesture recognizer, so a few 'pixels' of the image take up a significant amount of the screen.)
This is not what I want. Any ideas on how to fix it?
Maybe some 'internal' parameter of UIPanGestureRecognizer I could get at if I sub-classed it or some such? I thought I'd try to sub-class the recognizer in a manner such as...
class BetterPanGestureRecognizer: UIPanGestureRecognizer {
var initialTouchLocation: CGPoint!
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent) {
super.touchesBegan(touches, withEvent: event)
initialTouchLocation = touches.first!.locationInView(view)
print("pan: touch begin detected")
print(self.state.hashValue) // this lets me check the state
}
override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent) {
super.touchesMoved(touches, withEvent: event)
print("pan: touch move detected")
print(self.state.hashValue) // this remains at the "began" value until you get beyond about 10 pixels
let some_criterion = (touches.first!.isEqual(something) && event.isEqual(somethingElse))
if (some_criterion) {
self.state = UIGestureRecognizerState.Changed
}
}
}
...but I'm not sure what to use for some_criterion, etc.
Any suggestions?
.
Other alternatives that could work, but that I'd rather not have to do:
I could simply attach my UIPanGestureRecognizer to some parent,
non-zoomed view, and then use affine transforms & such to remap the
points of the pan touches onto the respective parts of the image.
So why am I not doing that? Because the code is written so that
lots of other objects hang off the image view and they all get the
same gesture recognizers and....everything works just great without
my having keep track of anything (e.g. affine transformations), and the problem only shows up if you're really-really zoomed in.
I could abandon UIPanGestureRecognizer, and effectively just write my own using touchesBegan and touchesMoved (which is kind of
what I'm doing), however I like how UIPanGestureRecognizer
differentiates itself from, say, pinch events, in a way that I don't
have to worry about coding up myself.
I could just specify some maximum zoom beyond which the user can't go. This fails to implement what I'm going for, i.e. I want to allow for fine-detail level of manipulation.
Thanks.
[Will choose your answer over mine (i.e., the following) if merited, so I won't 'accept' this answer just yet.]
Got it. The basic idea of the solution is to change the state whenever touches are moved, but use the delegate method regarding simultaneous gesture recognizers so as not to "lock" out any pinch (or rotation) gesture. This will allow for one- and/or multi-fingered panning, as you like, with no 'conflicts'.
This, then, is my code:
class BetterPanGestureRecognizer: UIPanGestureRecognizer, UIGestureRecognizerDelegate {
var initialTouchLocation: CGPoint!
override init(target: AnyObject?, action: Selector) {
super.init(target: target, action: action)
self.delegate = self
}
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent) {
super.touchesBegan(touches, withEvent: event)
initialTouchLocation = touches.first!.locationInView(view)
}
override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent) {
super.touchesMoved(touches, withEvent: event)
if UIGestureRecognizerState.Possible == self.state {
self.state = UIGestureRecognizerState.Changed
}
}
func gestureRecognizer(_: UIGestureRecognizer,
shouldRecognizeSimultaneouslyWithGestureRecognizer:UIGestureRecognizer) -> Bool {
if !(shouldRecognizeSimultaneouslyWithGestureRecognizer is UIPanGestureRecognizer) {
return true
} else {
return false
}
}
}
Generally setting that "shouldRecognizeSimultaneouslyWithGestureRecognizer" delegate to true always is what many people may want. I make the delegate return false if the other recognizer is another Pan, just because I was noticing that without that logic (i.e., and making the delegate return true no matter what), it was "passing through" Pan gestures to underlying views and I didn't want that. You may just want to have it return true no matter what. Cheers.
Swift 5 + small improvement
I had a case when accepted solution conflicted with basic taps on toolbar which also had this betterPanGesture so I added minimum horizontal offset parameter to trigger state changing to .changed
class BetterPanGestureRecognizer: UIPanGestureRecognizer {
private var initialTouchLocation: CGPoint?
private let minHorizontalOffset: CGFloat = 5
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
super.touchesBegan(touches, with: event)
self.initialTouchLocation = touches.first?.location(in: self.view)
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
super.touchesMoved(touches, with: event)
if self.state == .possible,
abs((touches.first?.location(in: self.view).x ?? 0) - (self.initialTouchLocation?.x ?? 0)) >= self.minHorizontalOffset {
self.state = .changed
}
}
}

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