Question

我有滚动视图来显示图像。我需要计时器每5秒一个接一个地显示图像。如何使用计时器启动UIScrollView事件以在5秒后移动？

Answer 1

将变量int h添加到您的接口，将yourScrollView添加为属性。然后：

[NSTimer scheduledTimerWithTimeInterval:5.0 target:self selector:@selector(onTimer) userInfo:nil repeats:YES];

- (void) onTimer {

    // Updates the variable h, adding 100 (put your own value here!)
    h += 100; 

    //This makes the scrollView scroll to the desired position  
    yourScrollView.contentOffset = CGPointMake(0, h);  

}

Answer 2

修改上述代码

 [NSTimer scheduledTimerWithTimeInterval:0.05 target:self selector:@selector(onTimer)   userInfo:nil repeats:YES];

-(void) onTimer {
  // NSLog(@"content offset %f",scrollVw.contentOffset.y);
  if (scrollVw.contentOffset.y<MAX_ALLOWED_OFFSET) {
   //scroll to desire position
    scrollVw.contentOffset = CGPointMake(0, scrollVw.contentOffset.y+1);
  }


  }

Answer 3

将当前值作为内容的w（x值）或h（y值）。这有助于使用UIScollView内容中的当前参考点进行手动/半自动滚动。

CGFloat w = scroller.contentOffset.x;

或

CGFloat h = scroller.contentOffset.y;

然后当然：

h += 100; // h-=100 for decrement
yourScrollView.contentOffset = CGPointMake(0, h);

Answer 4

Swift版

添加以下属性

var offSet: CGFloat = 0

@IBOutlet weak var imagePageControl: UIPageControl!
@IBOutlet weak var imageScrollView: UIScrollView!

let imageArray = [your images]

修改viewDidLoad()

    override func viewDidLoad() {
    super.viewDidLoad()
    self.offSet = 0
    let timer = Timer.scheduledTimer(timeInterval: 8, target: self, selector: #selector(autoScroll), userInfo: nil, repeats: true)

    imagePageControl.numberOfPages = bannerArray.count
    imageScrollView.isPagingEnabled = true
    imageScrollView.contentSize.height = 200
    imageScrollView.contentSize.width = self.view.bounds.width * CGFloat(bannerArray.count)
    imageScrollView.showsHorizontalScrollIndicator = false

    imageScrollView.delegate = self

    for (index, image) in imageArray.enumerated() {
        let image = image
        let imageView = UIImageView(image: image)
        imageView.contentMode = .scaleAspectFill
        imageView.frame.size.width = self.view.bounds.size.width
        imageView.frame.size.height = 200
        imageView.frame.origin.x = CGFloat(index) * self.view.bounds.size.width
        imageScrollView.addSubview(imageView)
    }
}

为自动滚动创建此功能

    func autoScroll() {
    let totalPossibleOffset = CGFloat(imageArray.count - 1) * self.view.bounds.size.width
    if offSet == totalPossibleOffset {
        offSet = 0 // come back to the first image after the last image
    }
    else {
    offSet += self.view.bounds.size.width
    }
    DispatchQueue.main.async() {
        UIView.animate(withDuration: 0.3, delay: 0, options: UIViewAnimationOptions.curveLinear, animations: {
            self.imageScrollView.contentOffset.x = CGFloat(self.offSet)
        }, completion: nil)
    }
}

添加此功能以进行手动滚动

    func scrollViewDidScroll(_ scrollView: UIScrollView) {
    let page = scrollView.contentOffset.x / scrollView.frame.size.width
    imagePageControl.currentPage = Int(page)
    self.offSet = page * scrollView.frame.size.width // this updates offset value so that automatic scroll begins from the image you arrived at manually
}

注意：虽然问题是特定于自动滚动，但我也添加了手动滚动。这样自动滚动和手动滚动一起工作。另外，我添加了UIPageControl。如果您不需要，请删除imagePageControl。

Answer 5

也许，[scroll scrollRectToVisibile：animated：]比[scroll setContentOffset]更好。因为setContentOffset会导致滚出边缘。试一试！

如何使用计时器自动滚动UIScrollView

5 个答案: