I'm trying to make a game where objects fall from the sky (top of screen) and you have to pan an object left and right to avoid them. Pan gesture works fine but as soon as the objects (which are just other views with GCRects) start falling the pan gesture won't work. It just keeps reseting itself to its original position. To have the objects fall all I am doing is "spawning" them at the top of the screen and letting UIKit Dynamics and gravity do the rest to drop them down to the bottom. Any ideas how to have the gesture work concurrently with the falling objects?
It sounds like you have accidentally (or intentionally) added the view you want to pan manually to the animator as a dynamic item. This means that the animator is responsible for positioning it, so on every frame of the animation it puts it back where it was, because it doesn't understand that you've moved it manually. So don't add it as a dynamic item, or else your pan gesture recognizer's action method should keep calling updateItemUsingCurrentState: on the animator - that is how you tell the animator that you have moved an item manually.
Related
I have a UIScreenEdgePanGestureRecognizer (as part of a custom pop gesture) that works 85-90% of the time. There's that 10-15% when it just doesn't fire no matter how perfectly you swipe. The UIScreenEdgePanGestureRecognizer is competing with a UIScrollView that contains the navigation controller which also detects gestures in the same direction (horizontal) so I suspect that may be the issue.
Is this relatively common to have a UIScreenEdgePanGestureRecognizer fire inconsistently, particularly when UIKit has to take its best guess if the gesture is a screen-edge pop or a regular pan? And is there a way to reconfigure UIScreenEdgePanGestureRecognizer to get it working with a higher success rate, perhaps by enlarging the rectangle?
Prevent UIScrollView's UIPanGestureRecognizer from blocking UIScreenEdgePanGestureRecognizer:
[scrollView.panGestureRecognizer requireGestureRecognizerToFail:self.navigationController.interactivePopGestureRecognizer];
This method creates a relationship with another gesture recognizer that delays the receiver’s transition out of UIGestureRecognizerStatePossible.
I've got a view on the bottom of my ViewController ( similar to Google Maps Bottom Sheet ). The goal is:
When panning up, the view moves towards the pan direction ( essentially follows the finger), when panning ends, the view goes fullscreen. So far so good, all works.
Adding swipe gestures. When swiping up, the view should go full screen.
The issue is that by definition, a swiping gesture is a pan gesture but not the other way around. So unless i go really slow with my panning , the swipe gesture will trigger and the view will go full screen even though im still dragging on the screen.
Simply panning up doesnt look much like the kind of swipe im looking for. The swipe gesture im describing should only trigger if the user "flicked" the view momentarily. If they keep on panning the pan gesture should take precedence.
Any ideas how to achieve this? For reference you could check tap on a pin on google maps on either android or ios.
Its a little hard to describe without showing so if it helps im very open to clarify things.
UPDATES
I think the distinction for a swipe that would override the pan as im describing is that it a) took a short amount of time to complete b)the gesture ended with the user lifting the finger off the screen c) (maybe wrong ) the area traversed should not be too big. Sounds a lot like a flick to me..
If you cannot describe the difference between the two gestures in clearly defined terms then it will be difficult to tell the UIGestureRecognizer how to do so. In addition, it is possible that your user will have difficulty figuring out how to properly interact with the screen if your gestures are too similar or complex.
That being said, you may be able to distinguish between a "swipe" and a "pan" by checking the gesture's velocity. You should be able to play around with the UIGestureRecognizerDelegate methods and achieve the effect you want.
Ok i've achieved what was needed. The short answer is that i was looking for a "flick" gesture instead of a pan gesture. Generally its a nono to add custom gestures but as im replicating the google maps bottom sheet component for ios, it would appear that a custom gesture is the only way.
Using Navillus's comment, I added a velocity and gesture end check in the pan recogniser. The result looked like this:
if(recognizer.state == .ended){
if(recognizer.velocity(in: self).y > CGFloat(500) ){
self.pullUpViewSetMode_SUMMARY()
return;
}
if(recognizer.velocity(in: self).y < CGFloat(-500) ){
self.pullUpViewSetMode_FULL()
return;
}
}
//the rest of the pan handling code, namely translating the view up and up follows here
Hope this helps somebody.
My app uses a paged horizontal scroll view. Each page has UIControls which the user can tap.
UIScrollView does a good job of handling cancellation of touches and swipes. If the user starts swiping fast enough, it's always a swipe. If the user touches down long enough to activate the highlighted state, the scroll view doesn't attempt to swipe.
I'm trying to duplicate this behavior with a UIPanGestureRecognizer subclass so that I can respond to downward swipes within my scrollview. However, I can't get the gesture to cancel in the event of the UIControls getting highlighted.
So far I've done the following:
self.refreshGesture.cancelsTouchesInView = YES;
self.refreshGesture.delaysTouchesBegan = NO;
self.refreshGesture.delaysTouchesEnded = NO;
This seems to duplicate the way UIScrollView passes touches to views, but it doesn't duplicate the way that UIScrollView's pan gesture recognizer gets cancelled. self.refreshGesture is always triggered no matter how slowly the user swipes, or what the state of the UIControls are.
I've tried setting the delegate on my gesture, and this may be the way to go. But I haven't found a combination that works. For example, just checking if the touch starts within a UIControl cancels too frequently. I've also tried overriding gestureRecognizerShouldBegin in my controls, but this seems like a hack and has far reaching implications (interferes with UITextView's gestures, for example).
In this GIF, you can see that the control activates on touch, and the scrollview cancels scroll if that happens. But my downward pan gesture is not cancelled in the same manner:
I wasn't able to duplicate this exactly, but there are two possibilities suggested by WWDC 2014 #235.
Add a transparent scrollview over your main content and move its gesture recognizer onto your root view. This is what did. It let me use UIScrollViewDelegate which ended up being sufficient.
Use a "timeout" gesture recognizer. The video suggests requiring the timeout gesture to fail, but in my case it worked better to use a long press gesture and cancel my pan if the long press fired. 0.1 seconds seemed to work better than their suggested 0.15 seconds.
I am using a UIPanGestureRecogniser to implement drag and drop. When the drag starts I need to identify the object that is being dragged. However the objects are relatively small. And if the user doesn't hit the object right in the centre of the object it isn't getting dragged.
The problem is that when the gesture handler is first called with the state UIGestureRecognizerStateBegan, the finger has already moved several pixels, and so [UIPanGestureRecognizer locationInView:] returns that point, which is not where the gesture truly started. That makes sense as it can only recognize a pan after a few pixels of movement. However, I need the absolute start of the gesture, not the position after the gesture has first been recognized.
I'm thinking that maybe I need to implement a tap gesture recognizer as well, purely to capture the first touch. But that seems like a hack for what is not an unusual requirement. Is there no other way of getting that first touch from within the pan gesture recognizer?
UIGestureRecognizerDelegate protocol provides methods gestureRecognizerShouldBegin: and gestureRecognizer:shouldReceiveTouch: that can help you evaluate the touches before the pan has transitioned to state UIPanGestureRecognizerStateBegan
I'm new to developing iOS apps,
I've successfully implemented a Swipe Gesture Recognizer,
What I was wondering is if there is an easy to use recognizer like the swipe gesture. That would let you implement the homescreen page turning effect but just on a small view in the view controller?
If your unclear on what effect I mean, when you look at the iPhone's homescreen you can drag your finger and it responds instantly (unlike swipe) and also has some spring feeling to it, is this some effect I can use, or do I manually have to program this into the code if so is there a tutorial that explains this?
Thanks,
I hope my question makes sense.
Have a look at UIPanGestureRecognizer:
https://developer.apple.com/library/ios/documentation/uikit/reference/UIPanGestureRecognizer_Class/Reference/Reference.html
UIPanGestureRecognizer is a concrete subclass of UIGestureRecognizer
that looks for panning (dragging) gestures. The user must be pressing
one or more fingers on a view while they pan it. Clients implementing
the action method for this gesture recognizer can ask it for the
current translation and velocity of the gesture.
A panning gesture is continuous. It begins
(UIGestureRecognizerStateBegan) when the minimum number of fingers
allowed (minimumNumberOfTouches) has moved enough to be considered a
pan. It changes (UIGestureRecognizerStateChanged) when a finger moves
while at least the minimum number of fingers are pressed down. It ends
(UIGestureRecognizerStateEnded) when all fingers are lifted.
Clients of this class can, in their action methods, query the
UIPanGestureRecognizer object for the current translation of the
gesture (translationInView:) and the velocity of the translation
(velocityInView:). They can specify the view whose coordinate system
should be used for the translation and velocity values. Clients may
also reset the translation to a desired value.
Edit: The spring feeling part you would need to implement yourself. Since iOS 7 there is UIDynamics which contains different animators, for what you describe you may need UIGravityBehavior and maybe UICollisionBehaviour. Look at the WWDC 2013 videos for this topic, I think you will find some examples there.