One possible solution to this is in your handlePan method, check the location of the point on the screen, and only commit the change if it is within the bounds you wish to restrict it to.
For ex.
-(void) handlePan:(UIGestureRecognizer*)panGes{
CGPoint point = [panGes locationInView:self.view];
//Only allow movement up to within 100 pixels of the right bound of the screen
if (point.x < [UIScreen mainScreen].bounds.size.width - 100) {
CGRect newframe = CGRectMake(point.x, point.y, theImageView.frame.size.width, theImageView.frame.size.height);
theImageView.frame = newframe;
}
}
I believe this would also correctly handle any screen rotation
EDIT
To move your image view by the center of its frame, the handlePan
method could look something like this.
-(void)handlePan:(UIPanGestureRecognizer *)gesture {
CGPoint point = [gesture locationInView:self.view];
//Only allow movement up to within 50 pixels of the bounds of the screen
//Ex. (IPhone 5)
CGRect boundsRect = CGRectMake(50, 50, 220, 448);
if (CGRectContainsPoint(boundsRect, point)) {
imgView.center = point;
}
}
Check whether the point is within your desired bounds, and if so, set the center of your image view frame to that point.