2

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 UIScrollViews 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
}];
4

3 回答 3

4

您的视图控制器可以是两个滚动视图的代表。同意@Ravi，您可以使用委托参数来确定正在滚动的滚动视图。

听起来您需要打包一些动画才能对 UI 有意义：

// 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;
    }];
}

然后在视图中滚动：

- (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...
于 2012-09-19T17:40:00.553 回答
3

你应该实施<UIScrollViewDelegate>. 利用该方法- (void)scrollViewDidScroll:(UIScrollView *)scrollView并在其中编写动画代码。如果你有多个滚动视图，你可以这样做：

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    if(scrollView == myScrollView1)
        // do something
    else if (scrollView == myScrollView2)
        // do something else
    else
        // do something else
}
于 2012-09-19T17:10:17.970 回答
0

就像 tableview 你应该配置和控制你的滚动动作。您可以在此处编写控制器的扩展并控制所有滚动操作。例如，您可以检查：

extension ExampleViewController: UIScrollViewDelegate {

    func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
        // your actions here
    }

    func scrollViewDidEndScrollingAnimation(_ scrollView: UIScrollView) {
        // your actions here
    }

    func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
        // your actions here
    }

    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        // your actions here
    }
}
于 2018-06-12T13:48:11.173 回答