如何在单击UIPageControl点时更改页面

Question

在这里,我有一个页面控件,它工作正常,但点击它不会改变页面,所以请帮助改变页面的功能:

- (void)viewDidLoad {
    scrollView=[[UIScrollView alloc]initWithFrame:CGRectMake(0, 0, 320, 420)];
    scrollView.delegate = self;
    [self.scrollView setBackgroundColor:[UIColor whiteColor]];
    [scrollView setCanCancelContentTouches:NO];
    scrollView.indicatorStyle = UIScrollViewIndicatorStyleWhite;
    scrollView.clipsToBounds = YES;
    scrollView.scrollEnabled = YES;
    [scrollView setShowsHorizontalScrollIndicator:NO];
    scrollView.pagingEnabled = YES;
    [self.view addSubview:scrollView];
    pageControl=[[UIPageControl alloc]initWithFrame:CGRectMake(0, 420, 320, 40)];
    [pageControl addTarget:self action:@selector(changepage:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:pageControl];

    UIView *blueView = [[UIView alloc] init];
    blueView.frame = CGRectMake(0, 0, 640, 480);
    blueView.backgroundColor = [UIColor whiteColor];
    [scrollView addSubview:blueView];
    self.pageControl.numberOfPages = 2;
    [scrollView setContentSize:CGSizeMake(640, 0)];
}

-(void)changepage:(id)sender
{
    int page = pageControl.currentPage;
    if (page < 0)
        return;
    if (page >= 2)
        return;
    CGRect frame = scrollView.frame;
    frame.origin.x = frame.size.width * page;
    frame.origin.y = 0;
    [scrollView scrollRectToVisible:frame animated:YES];

}

- (void)scrollViewDidScroll:(UIScrollView *)_scrollView
{
    if (pageControlIsChangingPage)
        return;
    CGFloat pageWidth = _scrollView.frame.size.width;
    int page = floor((_scrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
    pageControl.currentPage = page;
}

Answer 1

您可以创建一个事件更改页面:

- (IBAction)changePage:(id)sender {
    UIPageControl *pager=sender;
    int page = pager.currentPage;
    CGRect frame = imageGrid_scrollView.frame;
    frame.origin.x = frame.size.width * page;
    frame.origin.y = 0;
    [imageGrid_scrollView scrollRectToVisible:frame animated:YES];
}

将它绑定到Pagecontrol的值更改事件.

Answer 2

这对于swift 3和swift 4的 pagecontrol点单击操作更改页面索引非常有用。

@IBAction func pageControlSelectionAction(_ sender: UIPageControl) {
    let page: Int? = sender.currentPage
    var frame: CGRect = self.yourcollectionview.frame
    frame.origin.x = frame.size.width * CGFloat(page ?? 0)
    frame.origin.y = 0
    self.yourcollectionview.scrollRectToVisible(frame, animated: true)
}

Answer 3

只是为了完成Banker Mittal的回答，快速完成此操作的最简单方法是将所需的矩形滚动到可见。您不必担心“向左”和“向右”滚动，因为iOS本身会意识到您点击了哪个点，因此您只需滚动至正确的帧即可：

private func moveScrollViewToCurrentPage() {

 //You can use your UICollectionView variable too instead of my scrollview variable
            self.scrollView
                .scrollRectToVisible(CGRect(
                    x: Int(self.scrollView.frame.size.width) * self.pager.currentPage,
                    y: 0,
                     width:Int(self.scrollView.frame.size.width),
                    height: Int(self.scrollView.frame.size.height)),
                                     animated: true)

    }