I want to show an image that stays on the page for 5 seconds but appears everytime my scrollview scrolls. So obviously i need to marry animation for the UILabel
and some method of UIScrollView
. Im not sure which one to use to be honest. Also i have two UIScrollView
s on one UIViewController
so i dont know what i should set as delegate.
The following is the animation i have at the moment
[UIView animateWithDuration:0.3 animations:^{ // animate the following:
pageCountImage.frame = CGRectMake(0, 0, 100, 50); // move to new location
}];
Your view controller can be the delegate of both scroll views. Agree with @Ravi that you can use the delegate param to determine which scroll view is scrolling.
Sounds like you need a few animations packaged to make sense for the UI:
// hide or show the page count image after a given delay, invoke completion when done
- (void)setPageCountImageHidden:(BOOL)hidden delay:(NSTimeInterval)delay completion:(void (^)(BOOL))completion {
BOOL currentlyHidden = self.pageCountImage.alpha == 0.0;
if (hidden == currentlyHidden) return;
[UIView animateWithDuration:0.3 delay:delay options:UIViewAnimationOptionBeginFromCurrentState animations:^{
self.pageCountImage.alpha = (hidden)? 0.0 : 1.0;
} completion:completion];
}
// move the page count image to the correct position given a scroll view content offset
- (void)positionPageControlForContentOffset:(CGFloat)xOffset {
// assume page width is a constant (the width of a page in the scroll view)
NSInteger page = xOffset / kPAGEWIDTH;
// assume max page is a constant (the max number of pages in scroll view)
// scroll positions in the "bounce" will generate page numbers out of bounds, fix that here...
page = MAX(MIN(page, kMAXPAGE), 0);
// kPAGE_INDICATOR_WIDTH the distance the page image moves between pages
// kPAGE_INDICATOR_ORIGIN the page image x position at page zero
CGFloat xPosition = kPAGE_INDICATOR_ORIGIN + page * kPAGE_INDICATOR_WIDTH;
// assume y position and size are constants
CGRect pageIndicatorFrame = CGRectMake(xPosition, kYPOS, kWIDTH, kHEIGHT);
// finally, do the animation
[UIView animateWithDuration:0.3 animations:^{
self.pageCountImage.frame = pageIndicatorFrame;
}];
}
Then in view did scroll:
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
if (scrollView == /* the scroller with the page control */) {
[self setPageCountImageHidden:NO delay:0.0 completion:^(BOOL finished) {
[self positionPageControlForContentOffset:scrollView.contentOffset.x];
[self setPageCountImageHidden:YES delay:5.0 completion:^(BOOL finished){}];
}];
}
// and so on...