如何将uiimage从scrollview拖到iphone sdk中的另一个uiimageview

Question

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.

Answer 1

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.

Answer 2

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.

Answer 3

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