I have displaying image thumbnails in a UIScrollView, if user taps on a thumbnail, the application should open that image. if, however, user drags on a thumb, the scroll view should pan. Right now the scrollview only scrolls if user is able to drag on the small empty space between the thumbnails. the subviews (the one's displaying image thumbs) use a UITapGestureRecognizer to detect taps, and exclusiveTouch on subviews is set to NO, UIScrollView has its canCancelContentTouches set to false.
Try leaving canCancelContentTouches set to YES, that allows the scroll view to override its subviews if it seems the user is trying to scroll.
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I have a UIScrollView with a zoomed image view contained within it. UIScrollView "contentSize" is about twice the height of the scrollview itself, enabling user to swipe the image up and down. What I'm seeing is that the "touch zone" for the UIScrollView (where it detects swiping, and scrolls the image accordingly) is only at the very bottom of the UIScrollView. Is there any property/method I can use to make the UIScrollView detect swipes throughout it's frame?
if you want touch points inside scrollview tgen you can use following delegate method-
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
In My Application,i am having one scrollVIew containing multiple images.
and out of the scrollview i have one uiimageview.
i want to Drag any image from ScrollView and drop it on uiimageview which is out of the scrollview.
is it possible?
help And suggestions are appreciated
Thanks in advance.
gamozzii's reply is close to what you need to do, but there's one problem. An UIScrollView will eat touches, so tapping on an image will have no effect.
As a result you will have to subclass the UIScrollView
I have written a small functional app to illustrate dragging the image from a scroll view into an image view. You can download the project here.
Yes this should be possible, you will need to implement the touch/drag events directly.
Check out the touchesBegan, touchesMoved etc. delegate methods in UIResponder.
One approach would be to subclass imageview and implement touchesBegan, touchesMoved in it, and use this imageview subclass to display your images in the scroll view.
On the touchesBegan create a new image view and add it to the outer view and set its image to be the same as the one in the scroll view. You need to overlay it directly over your source image in the scroll view so adjust its frame origin to be relative to the outer view you will need to use the scrollview origin and also the content view size and offset of the source image view inside the content view in order to recalculate the new origin in the outer view.
Then on the touches moved, simply readjust the frame of this image in accordance with the coordinates from the touches moved so that the image follows the touch.
Do a boundary check against the frame of your target imageview - once the user drags it into this boundary, make that target imageviews image the same as the image in the view being dragged and remove the dragged image from the containing view and release it.
In case you're still interested in another solution (and for other users of course):
I did implement that behaviour before just like gamozzii recommended.
I set canCancelContentTouches = NO on the UIScrollView to make sure the subviews handle there touches on their own. If a subview (in your case an image) was touched, i moved the view out of the scrollview onto the superview and started tracking it's dragging. (You have to calculate the correct coordinates within the new superview, so it stays in place). After dragging finishes, i checked if the target area was reached, otherwise I moved it back into the scrollview.
The subviews are handling the dragging on there own via (touchesBegan:/Moved:/Ended:/Cancelled:).
If that's not detailed enough, here's my example code: Github: JDDroppableView
I have a UIScrollView wich contains 2 views the first at offset 0 and the other at offset 800.
I want the user to be able to scroll down but not always, because in the upper view i have another controls tha receive touch input and dragging and sometimes when you are dragging if your touch is just a little bit out of the control the scrollview scrolls and that's very annoying. So i want that the scrollview only scroll in certain zones.
What you basically need is to subclass the UIView that should intercept touches outside it's frame and override it's hit test method.
I have two UIImageView objects inside my view (both 320x480 one above the other). The lower image view is inside a UIScrollView with scrolling and zooming enabled. Now I want to handle touches inside the other image view but it no longer detects any single taps.
I can understand that the UIScrollView handles all the touches which I do on it. But the touches on the image view above the scroll view are also not recognized.
Attached is an image with my view hierarchy. Can someone please tell me why the other image view's touches are also handled by the scrollview when it isn't a subview of scroll view?
And if the scrollview is bent on handling touches, how do I recognize touches on the other image view?
Thanks.
By default UIImageViews have userInteractionEnabled=NO;
Try setting it to YES (either in IB or in code).
I'm not sure, it might be that you need to set the frame size and/or content size of the scroll view properly. This page has a diagram of what I'm talking about.
I have a problem in the touchesMoved handler with a view that is added onto a UIScrollView. I add a number of labels to the scroll view. Each of these labels contain some text and, on swiping my finger on the labels, I have to play a specific file for that text.
If I just add the view onto the window directly, I get all of the touch events in touchesMoved without any problem. When I add my view onto the UIScrollView and then add this to the window, there is some lag in the touchesMoved handler. I am not getting continuous touch points in touchesMoved as with the normal view. As a result, while swiping the finger from the view, it happens that some labels are missed.
Is the problem due to scroll view? The same code runs perfectly in normal conditions (without a scroll view).
Does anyone have any solution to this?
UIScrollView sets a timer on touchDown to be able to know if it should handle scrolling or if it should pass the events on to subviews.
There is a property on UIScrollView for controlling this behaviour:
#property(nonatomic) BOOL delaysContentTouches