Im adding a UIView as a subView to a scrollView. However, I wish to detect touches in the UIView. But i notice that when i do something like this:
[self.myScrollView addSubview:myView];
then, the touchesDidBegin method is never called when i touch the subview. However, if i do the following,
[self.view addSubview:myView];
then, the touchesDidBegin method is called. However, now the subView does not scroll along with the scroller obviously.
I want "myView" to be added to the scrollView as a subview so that it scrolls along with it and also detects touches on it. Any way to accomplish this?
The same has already discussed here, plz find the link to similar SO post.
Handling touch events within a child UIScrollView
Touch events not working on UIViews inside UIScrollView
uiscrollview
Related
I have a UIScrollView and I'm implementing the viewForZoomingInScrollView: delegate method which returns a UIImage which the user can zoom and pan. I've also got some UIButtons as sub views of the UIScrollView which I'm using as annotations, like Google Maps.
The problem I'm having is that a lot of the UIImage can be obscured by the UIButtons when zoomed right out. When trying to pinch to zoom the UIButtons are receiving the touch event instead and the zoom is not happening. You end up having to carefully place your fingers in clear space to zoom.
I note the Google Maps app seems to work ok when there are lots of annotation views, you can still pinch.
I guess I need to priorities the touches, the UIScrollView needs to respond to pinches and pans, while the buttons just taps.
Anyone have experience of this?
I had this exact issue, and it was kind of weird. It wasn't due to any gesture recognizer on the button, it was the UIScrollView's pinch gesture recognizer that was being forwarded to the UIButton for some reason. Also, the UIButton was responding to certain UIGestureRecognizerDelegate calls (like -gestureRecognizerShouldBegin:) but not others (like -gestureRecognizer:shouldReceiveTouch:). It's like the UIScrollView was selectively forwarding some delegate calls to the UIButton and some not.
I finally found a very easy way to solve this issue:
yourScrollView.pinchGestureRecognizer.delaysTouchesBegan = YES;
yourScrollView.pinchGestureRecognizer.delaysTouchesEnded = YES;
Luckily, the default pinch gesture recognizer on UIScrollView's are publicly accessible, and the two delaysTouches property are NO by default. When you set them to YES, if the gesture recognizer could possibly or does recognize a pinch gesture even when it starts on top of a UIButton, it won't forward those touches to the UIButton, and the UIButtons will no longer interfere with the UIScrollView's zooming.
try this
UIGestureRecognizer* tapRecognizer = nil;
for (UIGestureRecognizer* recognizer in yourButton) {
if ( ![recognizer isKindOfClass:[UITapGestureRecognizer class]] ) {
[yourButton removeGestureRecognizer:recognizer];
break;
}
}
so you remove all the gesture recognizers from the button different from UITapGestureRecognizer
take a look at UIView's hitTest:withEvent: method. Inside that method youll need to check for which view you want to return. The view you return will be the one recieving the touches. for example, you can subclass the button and override that method to return the ImageView for your particular scenario.
I fixed this problem in a different way, but this might not be your case.
My buttons were added on an image view, the image view being added by itself to another container view. In the:
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
... method, I returned the image view - bad. Changing to return my very first container view in hierarchy fixed the touches.
I have an atypical iOS interface. Perhaps it's not practical but I'm giving it a go. Hope someone can help!
I have a menu in the form of a UIVIew. It contains 5 small UIImageViews. A UIPinchGestureRecognizer is attached to the UIVIew. When pinched inward, the 5 UIImageViews animate from off screen to form a circle in the middle of the window. When pinched outward, they animate back offscreen. Everything works great there.
I'd like to be able to, at any point in the application, pinch the screen to reveal the menu, select one of the 'buttons' (UIImageView), and load the associated subview.
The real problem is, if the current visible view is a UIScrollView or UITableView, my app is having trouble figuring out whether the menu or other subview should handle the touch event. If I really focus and make sure two finger touch the screen at the EXACT same time, the pinch will work and pull the menu inward. But otherwise, it attempts to scroll the current visible view.
I would like all events except the pinch gesture, (and a tap gesture when the menu is visible), to pass through the menu view to the rest of the subviews.
I understand I can override the hitTest:withEvent method to determine the correct view to handle the event, but I'm unclear at this point how exactly to use it. Neither the Apple docs nor any answers I've read on stack overflow have made this method clear to me.
Any help is much appreciated.
As UITableView is a subclass of UIScrollView, it inherits all of UIScrollView's properties including its gesture recognisers.
UIScrollView declares a UIPinchGestureRecognizer and UIPanGestureRecognizer. I'm not sure of the implementation details but I imagine the UITableView disables the pinch gesture recogniser as you are not supposed to be able to zoom a tableview!
In any case, you can attach your own UIPinchGestureRecognizer to the table view:
UIPinchGestureRecognizer *yPGR = [[UIPinchGestureRecognizer alloc]
initWithTarget:probablySelf action:yourMenuShowSelectorHere];
UITableView *tv = ...
// ...
[tv addGestureRecognizer:yPGR];
Then, you can make sure that the UITableView scoll does NOT scroll until your pinch has failed:
[tv.panGestureRecognizer requireGestureRecognizerToFail:yPGR];
This way, the UITableView will not scroll until it is sure that it has not detected a pinch.
EDIT: UIScrollView only uses (or at least declares public access to) UIGestureRecognizers in iOS 5 and up.
I've been trying to create a UITextView subclass that handles swiping away the keyboard like in the Message.app.
I have a UIPanGestureRecognizer added to the keyWindow of my app, and the gesture delegate is configured for shouldRecognizeSimultaneouslyWithGestureRecognizer. Everything works fine except for when the UIScrollView is decelerating, during that phase it is possible to pan without the touches being registered.
You can take a look at a very simple github sample project here.
I have tried adding the UIPanGestureRecognizer directly to the viewController.view and to the scrollView, same issue occurs. I have also tried setting scrollView.panGestureRecognizer requireGestureRecognizerToFail: with my UITextView subclass gesture recognizer.
Any ideas as to why this may be happening?
Instead of creating a new UIPanGestureRecognizer, maybe you could use the one on the UIScrollView, and add your own pan logic to that gesture recognizer with - (void)addTarget:(id)target action:(SEL)action.
I placed a few uiimageview objects into a scrollview. How can the imageview know the scrollview is being scrolled? Since the imageview is a subview of the scrollview i can't set the scrollview delegate to the imageview.
I want to create something similar to the apps view on the iphone. Where you can hold down an app and then drag it, but if you hold and move your finger too far to the left or right the action is stopped and scrolling takes over.
"Since the imageview is a subview of the scrollview i can't set the scrollview delegate to the imageview."
And why not?
You have viewcontroller which shows the particular scrollview correct? this viewcontroller should be the delegate of the scrollview, and viewcontroller should also hold pointers (either explicitly in an array or through tag of some sort) to the uiimageviews.
Then, whenever scrollview notifies viewcontroller (through scrollviewdidscroll type of delegate method), implement your logic to update uiimageview.
To implement the exact touch sequence, you can subclass UIGestureRecognizer or write your own touch handler.. take a look at Apple's documentation on Event Handling Guide :
http://developer.apple.com/library/ios/#documentation/EventHandling/Conceptual/EventHandlingiPhoneOS/Introduction/Introduction.html#//apple_ref/doc/uid/TP40009541
It doesn't, it just draws and draws. The scrollView makes sure you only see the part you really want to see
You might want to look at three20, they have a class that is very similar to the springboard. -- Used in facebook.app
Thanks Everyone, but I found out that UIScrollView sends the touchesCancelled message to the subview when scrolling starts.
UIView -> UIImageView
I know I have things somewhat working ok since I can tap on my UIImageView and see an NSLog() statement in my touchesBegan method.
.
UIView -> UIScrollView -> UIImageView
I drag that same UIImageView into a UIScrollView and touchesBegan no longer gets called when I tap on my UIImageView. (I haven't changed anything else. All the same connections, methods, and code remains unchanged.)
Why does touchesBegan no longer work? And what can I do to get it working again?
Add uitapgesture to get event
Code is
UITapGestureRecognizer *ges11=[[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(Handeltap:)];
[imagename addGestureRecognizer:ges11];
Create one action name "Handeltap" U will get called there.
by default UIImageView don't handle user gestures.
set UIImageView instance's userInteractionEnabled to YES
Have a look at the documentation for UIScrollView.
Because a scroll view has no scroll bars, it must know whether a touch signals an intent to scroll versus an intent to track a subview in the content. To make this determination, it temporarily intercepts a touch-down event by starting a timer and, before the timer fires, seeing if the touching finger makes any movement. If the timer fires without a significant change in position, the scroll view sends tracking events to the touched subview of the content view. If the user then drags their finger far enough before the timer elapses, the scroll view cancels any tracking in the subview and performs the scrolling itself. Subclasses can override the touchesShouldBegin:withEvent:inContentView:, pagingEnabled, and touchesShouldCancelInContentView: methods (which are called by the scroll view) to affect how the scroll view handles scrolling gestures.
I'd also recommend reading the Scroll View Programming Guide.