Pang Gesture Recognizer stop - ios

Question

want to use a UIView like a UIScrollView for more reason, i create a Action with PanGestureRecognizer that's the simple code:
- (IBAction)moveUp:(UIPanGestureRecognizer *)recognizer {
CGPoint translation = [recognizer translationInView:self.containerView];
recognizer.view.center = CGPointMake(recognizer.view.center.x, recognizer.view.center.y + translation.y);
[recognizer setTranslation:CGPointMake(0, 0) inView:self.view];
}
But i want to stop dragging when my containerView bottom is in exact position, follow the screens:
This is the full viewController, all button you see is inside a containerView
This is when i open the application:
The header image is in a ViewController below and all button you see is inside a containerView, now i want to fix this position with absolute y, my containerView can't drag down.
Now the function can't stop, when i dragUp this is what happen:
My containerView can drag over the end of the containerView and i don't want that is possible, i want block the drag up in the end of containerView like this screen:
And when i drag down again i want to stop drag in starter position (screen 1).
Thanks for any idea.

Answer 1

What you are trying to achieve sounded fun to me at first glance, so I wanted to give it a try.
I modified your gesture recognizer's call back to the following:
- (IBAction)panned:(UIPanGestureRecognizer *)recognizer
{
CGPoint translation = [recognizer translationInView:yourContainerView];
CGFloat yWithinBounds = 0.0f;
if(recognizer.view.center.y + (recognizer.view.bounds.size.height / 2.0f) > yourContainerView.bounds.size.height)
{
yWithinBounds = yourContainerView.bounds.size.height - (recognizer.view.bounds.size.height / 2.0f);
[UIView animateWithDuration:1.0f animations:^
{
recognizer.view.center = CGPointMake(recognizer.view.center.x, yWithinBounds);
}];
}
else if(recognizer.view.center.y - (recognizer.view.bounds.size.height / 2.0f) < yourContainerView.bounds.origin.y)
{
yWithinBounds = yourContainerView.bounds.origin.y + (recognizer.view.bounds.size.height / 2.0f);
[UIView animateWithDuration:1.0f animations:^
{
recognizer.view.center = CGPointMake(recognizer.view.center.x, yWithinBounds);
}];
}
else
{
recognizer.view.center = CGPointMake(recognizer.view.center.x, recognizer.view.center.y + translation.y);
[recognizer setTranslation:CGPointMake(0.0f, 0.0f) inView:self.view];
}
}
In the first if, we are checking if the current center point of your contained view + half the size of it is going out of bounds of the containing view on the bottom; if it is, instead of simply disallowing it to go further, I took the liberty of putting this in an animation block to animate the contained view back to within the containing view so that it looks a bit better visually.
In the else-if, we are doing the same except this time for the top of the containing view - we are checking if the contained view is going out of bounds on top; if it is, we animate it back within the containing view.
If the else clause is reached, that would mean the contained view is within the containing view's bounds - here, we simply translate it like you originally do.
Here is how I set up the views as test:
yourContainerView = [[UIView alloc] initWithFrame:self.view.bounds];
yourContainerView.backgroundColor = [UIColor brownColor];
[self.view addSubview:yourContainerView];
UIView *viewWithinContainer = [[UIView alloc] initWithFrame:(CGRect){{yourContainerView.bounds.origin.x, yourContainerView.bounds.origin.y}, yourContainerView.bounds.size.width, 50.0f}];
viewWithinContainer.backgroundColor = [UIColor yellowColor];
[yourContainerView addSubview:viewWithinContainer];
UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(panned:)];
[viewWithinContainer addGestureRecognizer:panGesture];
Feel free to adjust the height (i.e., 50.0f to other values) of the view (hereby: the viewWithinContainer) within the container; the way the code is set up, you would not need to change any other values else where even if you change the height.
You could also change the animation duration to your need.
I am moving the thing up and down in my simulator at the moment; looks simple but fun to play around.
Update after question update:
Your new update seems to differ somewhat greatly from what you originally asked, but here is the solution:
The complexity is direction. There are other ways to find out; but I am using mine here, through which we don't need to create another variable.
If you are using storyboard, please set up an IBOutlet for your container view, because we would like to obtain the following values (carry out the following in initWithFrame and initWithCoder):
p1 = viewWithinContainer.center.y;
p2 = viewWithinContainer.center.y - (yourContainerView.bounds.size.height - viewWithinContainer.bounds.size.height);
Please set up p1 and p2 as ivars:
CGFloat p1;
CGFloat p2;
Here is the updated method for a contained view larger than the containing view:
- (IBAction)panned:(UIPanGestureRecognizer *)recognizer
{
CGPoint translation = [recognizer translationInView:yourContainerView];
if(translation.y < 0)
{
if(recognizer.view.center.y + (recognizer.view.bounds.size.height / 2.0f) + translation.y > yourContainerView.bounds.size.height) {
recognizer.view.center = CGPointMake(recognizer.view.center.x, recognizer.view.center.y + translation.y);
[recognizer setTranslation:CGPointMake(0, 0) inView:self.view];
}
else
{
recognizer.view.center = CGPointMake(recognizer.view.center.x, p2);
[recognizer setTranslation:translation inView:self.view];
}
}
else if(translation.y > 0)
{
if(recognizer.view.center.y - (recognizer.view.bounds.size.height / 2.0f) + translation.y < yourContainerView.bounds.origin.y)
{
recognizer.view.center = CGPointMake(recognizer.view.center.x, recognizer.view.center.y + translation.y);
[recognizer setTranslation:CGPointMake(0, 0) inView:self.view];
}
else
{
recognizer.view.center = CGPointMake(recognizer.view.center.x, p1);
[recognizer setTranslation:translation inView:self.view];
}
}
}
The method will ensure that, as you scroll down, the top of the contained view will stop at the edge of the container on top; and as you scroll up, at the edge of the container on the bottom.
I ran this in the simulator; and japp, it has been fun doing this. Enjoy. :-)