I have the following code in place to grab the event when a UIScrollView reaches then end of its content view:
- (void) scrollViewDidEndDecelerating:(UIScrollView *) scrollView
{
float currentEndPoint = scrollView.contentOffset.y + scrollView.frame.size.height;
// CGPoint bottomOffset = CGPointMake(0, scrollView.contentSize.height - scrollView.bounds.size.height);
// [scrollView setContentOffset:bottomOffset animated:NO];
if (currentEndPoint >= scrollView.contentSize.height)
{
// We are at the bottom
I notice that when I scroll to the bottom it hits it and bounces back up.
If I add this:
CGPoint bottomOffset = CGPointMake(0, scrollView.contentSize.height - scrollView.bounds.size.height);
[scrollView setContentOffset:bottomOffset animated:NO];
then the scroll goes back to the bottom.
Is there any way for it to stay at the bottom without the "bounce back up" as in once it hits the bottom, stop it from moving.
Thanks.
You should uncheck the bounce property of scrollview. Check the screenshot!
I didn't understand much what you mean, what I got that you want to stop scrolling of table view when it reaches to bottom. So here is the process:-
- (void) scrollViewDidEndDecelerating:(UIScrollView *) scrollView
{
float currentEndPoint = scrollView.contentOffset.y + scrollView.frame.size.height;
if (currentEndPoint >= scrollView.contentSize.height)
{
CGPoint offset = scrollView.contentOffset;
offset.x -= 1.0;
offset.y -= 1.0;
[scrollView setContentOffset:offset animated:NO];
offset.x += 1.0;
offset.y += 1.0;
[scrollView setContentOffset:offset animated:NO];
}
}
bounce back problem, u can resolve by
var progressScrollView = UIScrollView()
progressScrollView.bounces = false
Is there any easy way of getting Item or index of item when UICollectionView stops scrolling?
This is how I found what item is available on center of the page when UICollectionView Stop Scrolling.
Based on this Answer. https://stackoverflow.com/a/24396643/2618600
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
NSLog(#"Finished scrolling %#",scrollView);
if ([scrollView isKindOfClass:[UICollectionView class]])
{
UICollectionView *mainCollection = (UICollectionView *) scrollView;
CGRect visibleRect = (CGRect){.origin = mainCollection.contentOffset, .size = mainCollection.bounds.size};
CGPoint visiblePoint = CGPointMake(CGRectGetMidX(visibleRect), CGRectGetMidY(visibleRect));
NSIndexPath *visibleIndexPath = [mainCollection indexPathForItemAtPoint:visiblePoint];
NSLog(#"visibleIndexPath %ld",(long)visibleIndexPath.row);
}
You can use - (NSArray *)indexPathsForVisibleItems method of UICollectionView.
I need to get event then UITableView scrolling up and down. How can I do it?
this not working
- (void)scrollViewDidScrollToTop:(UIScrollView *)scrollView
try this method.
- (void)scrollViewDidScroll:(UIScrollView *)aScrollView
{
CGPoint offset = aScrollView.contentOffset;
if (offset.y > 0)
{
NSLog(#"scorlling up");
}
else
{
NSLog(#"scorlling down");
}
}
I have a UICollectionView with a custom cell calld MyCell.
I'v been struggling with the scrolling methods, My scroll is horizontal here is my code:
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset
{
if (velocity.x < 0)
{
baseOffset = MAX(0, baseOffset - offsetStep);
baseOffset-=320;
NSLog(#"%f", baseOffset);
}
else if (velocity.x > 0)
{
baseOffset = MIN(scrollView.contentSize.width - scrollView.bounds.size.width, baseOffset + offsetStep);
baseOffset+=320;
NSLog(#"%f", baseOffset);
}
#if 0
dispatch_async(dispatch_get_main_queue(), ^{
[scrollView setContentOffset:CGPointMake(baseOffset, 0) animated:YES];
});
#else
targetContentOffset->x = baseOffset;
#endif
}
The problems are:
1. the cell is not automatically centered when scrolling
2. If i reach the end of the cells and scroll again, when i scroll back it
scrolls back to the last cell and if i scroll back again it scroll to the right cell.
3. same as 2 but when I'm in the first cell and scroll back.
Any help here gurus?
thanks.
My question has to do with a custom form of paging which I am trying to do with a scroller, and this is easier to visualise if you first consider the type of scroll view implemented in a slot machine.
So say my UIScrollView has a width of 100 pixels. Assume it contains 3 inner views, each with a width of 30 pixels, such that they are separated by a width of 3 pixels. The type of paging which I would like to achieve, is such that each page is one of my views (30 pixels), and not the whole width of the scroll view.
I know that usually, if the view takes up the whole width of the scroll view, and paging is enabled then everything works. However, in my custom paging, I also want surrounding views in the scroll view to be visible as well.
How would I do this?
I just did this for another project. What you need to do is to place the UIScrollView into a custom implementation of UIView. I created a class for this called ExtendedHitAreaViewController. The ExtendedHitAreaView overrides the hitTest function to return its first child object, which will be your scroll view.
Your scroll view should be the page size you want, i.e., 30px with clipsToBounds = NO.
The extended hit area view should be the full size of the area you want to be visible, with clipsToBounds = YES.
Add the scroll view as a subview to the extended hit area view, then add the extended hit area view to your viewcontroller's view.
#implementation ExtendedHitAreaViewContainer
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
if ([self pointInside:point withEvent:event]) {
if ([[self subviews] count] > 0) {
//force return of first child, if exists
return [[self subviews] objectAtIndex:0];
} else {
return self;
}
}
return nil;
}
#end
Since iOS 5 there is this delegate method: - (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset.
So you can do something like this:
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint
*)targetContentOffset {
if (scrollView == self.scrollView) {
CGFloat x = targetContentOffset->x;
x = roundf(x / 30.0f) * 30.0f;
targetContentOffset->x = x;
}
}
For higher velocities you might want to adjust your targetContentOffset a bit different if you want a more snappy feeling.
I had the same problem and this worked great for me, tested on iOS 8.
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView
withVelocity:(CGPoint)velocity
targetContentOffset:(inout CGPoint *)targetContentOffset
{
NSInteger index = lrint(targetContentOffset->x/_pageWidth);
NSInteger currentPage = lrint(scrollView.contentOffset.x/_pageWidth);
if(index == currentPage) {
if(velocity.x > 0)
index++;
else if(velocity.x < 0)
index--;
}
targetContentOffset->x = index * _pageWidth;
}
I had to check the velocity and always go to next/previous page if velocity was not zero, otherwise it would give non-animated jumps when doing very short and fast swipes.
Update: This seems to work even better:
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView
withVelocity:(CGPoint)velocity
targetContentOffset:(inout CGPoint *)targetContentOffset
{
CGFloat index = targetContentOffset->x/channelScrollWidth;
if(velocity.x > 0)
index = ceil(index);
else if(velocity.x < 0)
index = floor(index);
else
index = round(index);
targetContentOffset->x = index * channelScrollWidth;
}
Those are for a horizontal scrollview, use y instead of x for a vertical one.
I've been struggling to overcome this issue, and I found an almost perfect solution which is to ideal with and paging width you want.
I'd set scrollView.isPaging to false (meanwhile, it's false by default) from UIScrollView and set its delegate to UIScrollViewDelegate.
func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
// Stop scrollView sliding:
targetContentOffset.pointee = scrollView.contentOffset
if scrollView == scrollView {
let maxIndex = slides.count - 1
let targetX: CGFloat = scrollView.contentOffset.x + velocity.x * 60.0
var targetIndex = Int(round(Double(targetX / (pageWidth + spacingWidth))))
var additionalWidth: CGFloat = 0
var isOverScrolled = false
if targetIndex <= 0 {
targetIndex = 0
} else {
// in case you want to make page to center of View
// by substract width with this additionalWidth
additionalWidth = 20
}
if targetIndex > maxIndex {
targetIndex = maxIndex
isOverScrolled = true
}
let velocityX = velocity.x
var newOffset = CGPoint(x: (CGFloat(targetIndex) * (self.pageWidth + self.spacingWidth)) - additionalWidth, y: 0)
if velocityX == 0 {
// when velocityX is 0, the jumping animation will occured
// if we don't set targetContentOffset.pointee to new offset
if !isOverScrolled && targetIndex == maxIndex {
newOffset.x = scrollView.contentSize.width - scrollView.frame.width
}
targetContentOffset.pointee = newOffset
}
// Damping equal 1 => no oscillations => decay animation:
UIView.animate(
withDuration: 0.3, delay: 0,
usingSpringWithDamping: 1,
initialSpringVelocity: velocityX,
options: .allowUserInteraction,
animations: {
scrollView.contentOffset = newOffset
scrollView.layoutIfNeeded()
}, completion: nil)
}
}
slides contains all page views that you have inserted to UIScrollView.
I have many different views inside scroll view with buttons and gesture recognisers.
#picciano's answer didn't work (scroll worked good but buttons and recognisers didn't get touches) for me so I found this solution:
class ExtendedHitAreaView : UIScrollView {
// Your insets
var hitAreaEdgeInset = UIEdgeInsets(top: 0, left: -20, bottom: 0, right: -20)
override func pointInside(point: CGPoint, withEvent event: UIEvent?) -> Bool {
let hitBounds = UIEdgeInsetsInsetRect(bounds, hitAreaEdgeInset)
return CGRectContainsPoint(hitBounds, point)
}
}
After a couple of days of researching and troubleshooting i came up with something that works for me!
First you need to subclass the view that the scrollview is in and override this method with the following:
-(UIView*)hitTest:(CGPoint)point withEvent:(UIEvent*)event {
UIView* child = nil;
if ((child = [super hitTest:point withEvent:event]) == self)
return (UIView *)_calloutCell;
return child;
}
Then all the magic happens in the scrollview delegate methods
-(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
//_lastOffset is declared in the header file
//#property (nonatomic) CGPoint lastOffset;
_lastOffset = scrollView.contentOffset;
}
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset {
CGPoint currentOffset = scrollView.contentOffset;
CGPoint newOffset = CGPointZero;
if (_lastOffset.x < currentOffset.x) {
// right to left
newOffset.x = _lastOffset.x + 298;
}
else {
// left to right
newOffset.x = _lastOffset.x - 298;
}
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:0.5];
[UIView setAnimationDelay:0.0f];
targetContentOffset->x = newOffset.x;
[UIView commitAnimations];
}
You also need to set the scrollview's deceleration rate. I did it in ViewDidLoad
[self.scrollView setDecelerationRate:UIScrollViewDecelerationRateFast];
alcides' solution works perfectly. i just enable / disable the scrolling of the scrollview, whenever i enter scrollviewDidEndDragging and scrollViewWillEndDragging. if the user scrolls several times before the paging animation is finished, the cells are slightly out of alignment.
so i have:
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset {
scrollView.scrollEnabled = NO
CGPoint currentOffset = scrollView.contentOffset;
CGPoint newOffset = CGPointZero;
if (_lastOffset.x < currentOffset.x) {
// right to left
newOffset.x = _lastOffset.x + 298;
}
else {
// left to right
newOffset.x = _lastOffset.x - 298;
}
[UIView animateWithDuration:0.4 animations:^{
targetContentOffset.x = newOffset.x
}];
}
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView {
scrollView.scrollEnabled = YES
}