如何在以UIScrollView作为子视图的父视图中检测滑动？

Question

I have 3 nested views, Main view (parent) -> UIScrollView -> ImageView. I am building a content viewer, where a user swipes to get the next/previous image from a list. But i want this next image to load only after the user has reached either the rightmost/bottom(end of the image) or the leftmost/top corner. There is a transition animation involved, where in the next/previous image follows the swipe while loading the next item. How should I go about achieving this?

PS:I have already tried adding gesture recognizers in the parent view, but it doesn't work.

Answer 1

You should use Swipe Gestures

UISwipeGestureRecognizer *swipe_left = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipe_left)];
    swipe_left.direction = UISwipeGestureRecognizerDirectionLeft;
    [yourView addGestureRecognizer:swipe_left];
 UISwipeGestureRecognizer *swipe_right = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipe_right)];
    swipe_right.direction = UISwipeGestureRecognizerDirectionRight;
    [yourView addGestureRecognizer:swipe_right];

-(void)swipe_left
{
    //Write your content offset if required
}


-(void)swipe_right
{

   someView.contentOffset = CGPointMake(470, 0);      //Example
}

Regards

Deepak

Happy New Year!!

Answer 2

It seems like you are using the scrollview to move the current image around and then when the user encounters either of the two trigger points (left-top/right-bottom) you want to trigger your animation and load in the next image. If that is the case, why don't you just use the scrollView delegate method -scrollViewDidScroll:(UIScrollView *)scroller ? In that method you can check the scrollView's contentOffset property and compare it against the current image's dimensions. When the contentOffset falls within your parameters for triggering the animation and load, do so.