By default, scrollView.contentOffset = 0 means left edge (side) of scrollView (UIScrollView).
Is there anyway to change this behavior? Something like making Right-to-Left UIScrollView, that it's contentOffset = 0 means right edge (side) of scrollView.
let rightOffset = scrollView.contentSize.width - scrollView.contentOffset.x
that way you can
Calculate contentOffset from right side of screen in UIScrollView
Related
The idea is replacing PageController with UIScrollView, UIScrollView should only scroll to the next/previous item and stop. I've found a few solutions, but I've only understood that I've to use targetContentOffsetForProposedContentOffset, but have no idea what CGPoint should I return and how to stop on the next item even if user scrolls with high velocity.
override func targetContentOffsetForProposedContentOffset(proposedContentOffset: CGPoint, withScrollingVelocity velocity: CGPoint) -> CGPoint {
return CGPoint(x: 0, y: 0)
}
Use below of code. Your problem will be solved.
YourScrollView.pagingEnabled = YES;
With UIScrollView, you can enable paging. The property is called pagingEnabled. This means if it will snap to full widths (or heights) providing you set the content size properly.
i.e. If you want 2 pages and have a width of 100 and height of 200. You set the content size to be CGSize 200 for width and 200 for height. The scroll view will handle the snapping and paging.
If you want to have a function to go to a page like goToPage(2). Then you just need to call scrollRectToVisible method in UIScrollView with a CGRect of (pageNumber * scrollView.width (or page width), 1 height)
It looks like you are using Swift, so your implementation may vary.
I set the content size so vertical scrolling becomes activated but I only want the user to be able to scroll north and not south. Any ideas on how I can accomplish this?
//set high greater than view
myScroll.contentSize = CGSize(width: myView.view.frame.width,height: myView.view.frame.height + 190)
I only want the ability to scroll up and disable the ability to scroll down which is the default direction of the scrollview
You can set the content offset of the scroll view to the bottom. i.e.,
myScroll.contentOffset = CGPoint(x: 0,y: 190) // Here 190 is the same value that represent the height increase done in contentSize.
Make a subclass of UIScrollView. Override layoutSubviews to make sure contentOffset.y only increases, except when it's beyond the end of the content range, so the scroll view can bounce at the bottom.
class MyScrollView: UIScrollView {
var priorOffset = CGPoint.zero
override func layoutSubviews() {
var offset = contentOffset
if offset.y < priorOffset.y {
let yMax = contentSize.height - bounds.height
if offset.y < yMax {
offset.y = priorOffset.y
contentOffset = offset
}
}
priorOffset = offset
super.layoutSubviews()
}
}
Result:
select your Scrollview
select identity inspector
set user define attributes (see image)
in image first 435 vertical scrolling & second 116 is horizontal scroll
Note : set your own scrolling
You can set the direction of UIPanGestureRecognizer which is attached to your UIScrollView.
Check out some popular question which has an up-to-date answer, for example this one.
Or just go with pod 'UIPanGestureRecognizerDirection'
I have a ScrollView that is supposed to be scrolled only downwards. The content View's size matches scrollview identically. I use this code to prevent from scrolling up:
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
#define CONTENT_OFFSET 0
NSLog(#"%f", scrollView.contentOffset.y);
//prevent from scrolling up
if (scrollView.contentOffset.y > CONTENT_OFFSET) {
scrollView.contentOffset = CGPointMake(0, CONTENT_OFFSET);
}
}
It used to work perfectly. But now for some reason scroll view starts at -44 points and is of course scrollable up to 0. In between -44 and 0 it doesn't bounce if drag ended. I'm pretty sure I have not changed anything in layout but I might have unintentionally. I think scroll view now has bigger content view for some reason. Where do I look for the origin of this problem?
I would like to know how to implement parallax scrolling similar to Yahoo News Digest app. In which when user scroll horizontally background image scrolls in a different speed with the paging is enabled.
May be they do it with a ScrollView with a background view. Not exactly sure. Hint to implement such scrolling would be great. I have checked similar questions but couldn't find the answer I was looking for.
I've done this before with 2 scrollviews.
You have the main detail scroll view and then the parallax scroll view behind it (or wherever you want it).
Then you become the delegate of the detail scrollview.
In the method scrollView:didScroll you can then adjust the scroll of the parallax view.
If you're just doing the x axis then you want something like this...
CGFloat detailMaxOffset = self.detailScrollView.contentSize.width - CGRectGetWidth(self.scrollView.frame);
CGFloat percentage = self.detailScrollView.contentOffset.x / maxOffset;
CGFloat parallaxMaxOffset = self.parallaxScrollView.contentSize.width - CGRectGetWidth(self.parallaxScrollView.frame);
[self.parallaxScrollView setContentOffset:CGPointMake(percentage * parallaxOffset, 0);
This will set the scrollviews content offset "percentage" to be the same on each.
To get the parallax effect you just need to make the contentSize of each scrollview different.
If the parallax scroll view has a bigger content size than the detail scroll view it will scroll faster. If it has a smaller content size it will scroll slower.
Here is the answer. I subclass it from uitableview so that data can be reusable and wrap it in a uiview. https://github.com/michaelhenry/MHYahooParallaxView
Thanks,
Kel
100% working and dam easy
Take a view on imageview exactly size of image view.
by default alpha for view set 0.
//MARK: Scroll View Delegate methods
-(void)scrollViewDidScroll:(UIScrollView *)scrollView{
NSLog(#"X: %f Y: %f",scrollView.contentOffset.x,scrollView.contentOffset.y);
CGFloat scrollY = _mainScrollView.contentOffset.y;
CGFloat height = _alphaView.frame.size.height;
CGFloat alphaMonitor = scrollY/height;
_alphaView.alpha = alphaMonitor;
}
Swift 3
Here's how I got a parallax effect to work in Swift 3 for a vertical scroll in a tvOS app.
In ViewDidLoad():
parallaxScrollView.delegate = self
detailScrollView.delegate = self
And following:
override func viewDidLayoutSubviews() {
self.detailScrollView!.contentSize = CGSize(width: 1920, height: 2700)
self.parallaxScrollView?.contentSize = CGSize(width: 1920, height: 3000)
}
//// THE SCROLL VIEW
func scrollViewDidScroll(_ scrollView: UIScrollView) {
// Parallax effect
let detailMaxOffset = self.detailScrollView.contentSize.height - self.detailScrollView.frame.height;
let percentage = self.detailScrollView.contentOffset.y / detailMaxOffset
let parallaxMaxOffset = self.parallaxScrollView.contentSize.height - self.parallaxScrollView.frame.height;
let parallaxOffset = CGPoint(x:0,y:(percentage * parallaxMaxOffset))
self.parallaxScrollView.setContentOffset((parallaxOffset), animated: false)
}
I have one UIImageView (building's floor map) and UIScrollView with gesture recognisers which allow me to scroll horizontally and vertically, zoom in/out. Everything works OK, but the building has two floors, so user should have the option to switch between them. I decided to use segmented control at the top of the map to provide this option.
If I put Segmented Control to the same UIScrollView, it scrolls vertically as well as horizontally. What I am asking is how to fix horizontal position of the Segmented Control, so it will be able to scroll only vertically with map.
I am trying to use this code to test, if it fixes the position of Segmented Control absolutely, but it seems to be that it doesn't.
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
CGRect frame = _floorSelector.frame;
frame.origin.y=50;
frame.origin.x= 160;
_floorSelector.frame = frame;
}
Where is the mistake? Thank you for replies!
I think the issue here is you are misunderstanding how scrolling is implemented in a UIScrollView, and how things are placed in its coordinate space.
When a UIScrollView is scrolled, the frames of its subviews are not changed. Relative to the scrollview, they remain in the same position while the contentOffset and bounds of the scroll view changes. In order to make a subview of a scroll view appear static while the rest of it scrolls, you must change its frame within the scrollview as the bounds change.
With that in mind, what you are doing now is just setting the same frame on that subview repeatedly, which is the same as not doing anything.
It sounds like what you want to do is something like this:
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
CGRect frame = _floorSelector.frame;
frame.origin.x = 160 + scrollView.contentOffset.x;
_floorSelector.frame = frame;
}
Notice I do not change anything in the y axis because based on your question, the vertical scrolling doesn't need to be changed.