I can't figure out a solution. I have a UIScrollView, and on each scroll towards right, I will increase the contentSize of the scrollView and add a View at that place. The problem is I have managed to save the last content offset by delegation when scrollview start dragging but I don't understand which delegate method to use for measuring where the gesture stopped. If I use scrollViewDidEndDecelerating, will be called immediately after the scrollViewWillBeginDragging because the content is settled to the same size of the frame.
Does anybody have any solution on it?
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I'm looking for a way of 'sticking' a UIScrollView to it's position unless the touch has been moved by a certain threshold, at which point it will jump to where it should have scrolled to and continue scrolling.
The reason for this is that I have a vertical scroll and each cell inside the UIScrollView has a horizontal scroll. So I'd like to introduce a slight 'stickyness' to make sure the user doesn't accidentally scroll vertically when they mean to scroll horizontally.
I started by hijacking the contentOffset property in scrollViewDidScroll. The trouble with that is I cannot find out how much the scrollView would have moved by if I were setting the contentOffset
If I try to add a UIPanGestureRecognizer to the class then it overrides the UIScrollView and the UIScrollView becomes unresponsive.
Does anyone know a way to do this?
EDIT: edits based on comments.
I want to implement a scroll view which looks like the stock ticker. It can respond slide or tap gesture.
How can I implement this? Please advise me. Thank you!
Use a NSTimer to reposition the contentOffset of your Scrollview.
Use the UIScrollViewDelegate to stop your animation while the user is dragging the scrollview.
Conceptually I'd setup an container UIScrollView with the contents of the scrolling area as subviews. To simulate a circular scroll I'd keep an array of the subviews. I'd add a view just off screen at the starting edge, and take away a view just off screen at ending edge.
UIScrollViewDelegate methods will be called when a person starts or stops dragging the view, which you can use to start and stop the animated scrolling. Other methods in this protocol can be used to reset the contents of the scrollview when the edge is reached, so more views can be added as needed.
I'd probably use a CADisplayLink to manually manage the animations. The method given to the CADisplayLink would update the scroll and manage adding and subtracting views to the edges. It would also stop scrolling based on a flag set by the UIScrollViewDelegate methods when the person is dragging the scroll.
Unless you jailbreak, you can't put custom views in Notification Centre.
I have a UIScrollView that has a single child view within it. If I set the contentSize of the UIScrollView immediately after creation, everything works as I expect and I get scrolling.
The challenge is the view within the UIScrollView is dynamically sized. The width is fixed, but the height is unknown at the time I set up the scrollview.
When I do a [scrollView setContentSize:CGRectMake(...)] after the inner view does it's thing, the scrollview updates to the proper size and scrolling works. So basic scrolling works fine.
However, the major problem is that when I setContentSize at a later point, the UIScrollView decides to scroll down(with animation) towards the end of the scrollview, which is not what I want, I want the scroll to stay at the top, and let the contents within the scrollview either get bigger or smaller, without changing the apparent scroll position.
What am I missing?
Why don't you also call [scrollview setContentOffset:CGPointMake(0,0)]; when you call the setContentSize?
To force UIScrollView to scroll only e.g. horizontally, I always set non-scrollable value for contentSize to 0, using:
CGSizeMake(contentSize.width, 0).
I have a UIScrollView instance with many views inside. I have touchesBegan: defined inside my implementation of a subclass of UIView, but touches are only detected for views that are originally shown inside the scrollview (without scrolling). That is, initially all touches are detected, but when I scroll down, no touches are detected, except for on those views which were originally above the fold (i.e. they originally fit in the scrollview), and moreover, only those parts of those views which were above the fold (in the cases of views that were partially shown originally).
I hope this is clear... anyone have any idea what could be causing a situation like this?
After a day of debugging, I found the simple solution. The height of the frame of the view inside the scrollview had been set to the height of the screen. I needed to extend it to the full height of the scrollview.
This is more of a check as I believe this is right but its a lot of work if I'm wrong.
I want to basically achieve fixed positioning with a scrollView. I want to have a list along the top that is always visible, scrolls horizontal only and then a scrollview beneath that to move around the information which scrolls both vertically and horizontally.
I figure I need to subclass UIScrollView and overwrite touchesBegan, touchesMoved and touchesEnded to send the touch to both UIScrollViews.
Is this right or off track?
Cheers
Overriding the touch events on a scroll view is probably not what you want to do. Instead you can simply use a single scroll view, and then in the parent view's -layoutSubviews or in the scroll view's delegate methods you can move the list so it's always at the same vertical position (use the scroll view's contentOffset property to determine where that should be). Both the delegate method and -layoutSubviews is called before the drawing actually occurs after the scroll view scrolls, so by always repositioning your view where you want it to be, it will appear to remain fixed to the user.