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copied!<p>So, you're only concerned with left / right panning...</p> <p>Let's assume you have 2 UIImageViews, a & b, as subviews of some other UIView and defined as class members of some class.</p> <p>You can get help detecting panning gestures (dragging touches) on each of these views by creating instances of UIPanGestureRecognizer and adding them to each UIImageView using method addGestureRecognizer:</p> <p>When creating each UIPanGestureRecognizer, you need to designate a selector to receive the gesture events. Let say it's called didMove:</p> <p>Now, some sample code:</p> <pre><code>- (void) didMove:(UIPanGestureRecognizer*)recognizer { UIView* view = [recognizer view]; // Remember our UIImageViews are class members called, a & b // UIView* otherView = view == a ? b : a; if (recognizer.state == UIGestureRecognizerStateBegin || recognizer.state == UIGestureRecognizerStateChanged) { // Moving left will have a negative x, moving right positive // CGPoint translation = [recognizer translationInView:view.superview]; view.center = CGPointMake(view.center.x + translation.x, view.center.y); // Reset so we always track the translation from the current view position // [recognizer setTranslation:CGPointZero inView:view.superview]; if (CGRectIntersectsRect(view.frame, otherView.frame)) { // Translate by the same number of points to keep views in sync // otherView.center = CGPointMake(otherView.center.x + translation.x, otherView.center.y); } } } </code></pre> <p>It may not be exactly what you need, but it should give you a good idea how it could be done.</p>

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