我可以在UIScrollView中使用UIRefreshControl吗?

时间:2013-02-16 00:04:06

标签: ios iphone uiscrollview xamarin.ios uirefreshcontrol

我的应用程序中已经有大约5 UIScrollView个,它们都加载了多个.xib个文件。我们现在想要使用UIRefreshControl。它们构建为与UITableViewControllers一起使用(根据UIRefreshControl类引用)。我不想重新做所有5 UIScrollView的工作。我已经尝试在我的UIRefreshControl中使用UIScrollView,除了一些内容之外,它可以按预期工作。

  1. 在刷新图像变成加载程序之后,UIScrollView会向下跳跃大约10个像素,这种情况只有在我非常小心地将UIScrollview非常缓慢地向下拖动时才会发生。

  2. 当我向下滚动并开始重新加载时,放开UIScrollViewUIScrollView停留在我放手的地方。重新加载完成后,UIScrollView跳到顶部,没有动画。

  3. 这是我的代码:

    -(void)viewDidLoad
    {
          UIRefreshControl *refreshControl = [[UIRefreshControl alloc] init];
          [refreshControl addTarget:self action:@selector(handleRefresh:) forControlEvents:UIControlEventValueChanged];
          [myScrollView addSubview:refreshControl];
    }
    
    -(void)handleRefresh:(UIRefreshControl *)refresh {
          // Reload my data
          [refresh endRefreshing];
    }
    

    有什么方法可以节省大量时间并在UIRefreshControl中使用UIScrollView吗?

    谢谢!!!

11 个答案:

答案 0 :(得分:92)

我有UIRefreshControl使用UIScrollView

- (void)viewDidLoad
{
    UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, 500, 500)];
    scrollView.userInteractionEnabled = TRUE;
    scrollView.scrollEnabled = TRUE;
    scrollView.backgroundColor = [UIColor whiteColor];
    scrollView.contentSize = CGSizeMake(500, 1000);

    UIRefreshControl *refreshControl = [[UIRefreshControl alloc] init];
    [refreshControl addTarget:self action:@selector(testRefresh:) forControlEvents:UIControlEventValueChanged];
    [scrollView addSubview:refreshControl];

    [self.view addSubview:scrollView];
}

- (void)testRefresh:(UIRefreshControl *)refreshControl
{    
    refreshControl.attributedTitle = [[NSAttributedString alloc] initWithString:@"Refreshing data..."];

        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        [NSThread sleepForTimeInterval:3];//for 3 seconds, prevent scrollview from bouncing back down (which would cover up the refresh view immediately and stop the user from even seeing the refresh text / animation)

        dispatch_async(dispatch_get_main_queue(), ^{
            NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
            [formatter setDateFormat:@"MMM d, h:mm a"];
            NSString *lastUpdate = [NSString stringWithFormat:@"Last updated on %@", [formatter stringFromDate:[NSDate date]]];

            refreshControl.attributedTitle = [[NSAttributedString alloc] initWithString:lastUpdate];

            [refreshControl endRefreshing];

            NSLog(@"refresh end");
        });
    });
}

需要在单独的线程上进行数据更新,否则它将锁定主线程(UI用于更新UI)。因此,当主线程忙于更新数据时,UI也会被锁定或冻结,您永远不会看到平滑的动画或微调器。

编辑:好的,我正在做与OP相同的事情,我现在已经添加了一些文本(即“拉到刷新”),它确实需要回到主线程来更新该文本

更新了答案。

答案 1 :(得分:39)

添加上述答案,在某些情况下,您无法设置contentSize(可能使用自动布局?)或者contentSize的高度小于或等于UIScrollView的高度。在这些情况下,UIRefreshControl将无法工作,因为UIScrollView不会反弹。

要解决此问题,请将属性 alwaysBounceVertical 设置为 TRUE

答案 2 :(得分:14)

如果您有幸支持iOS 10+,您现在只需设置refreshControl的{​​{1}}即可。这与UIScrollView上以前存在的refreshControl的工作方式相同。

答案 3 :(得分:12)

iOS 10 起,UIScrollView已具有refreshControl属性。当您创建UIRefereshControl并将其分配给该属性时,将显示此refreshControl。

无需将UIRefereshControl添加为子视图。

url.substring(url.indexOf("oauth_verifier=") + 15 , url.length());
  

UIRefreshControl对象是附加到任何UIScrollView对象的标准控件

来自https://developer.apple.com/documentation/uikit/uirefreshcontrol的代码和报价

答案 4 :(得分:10)

以下是在C#/ Monotouch中执行此操作的方法。我无法在任何地方找到C#的任何样本,所以这里是..谢谢Log139!

public override void ViewDidLoad ()
{
    //Create a scrollview object
    UIScrollView MainScrollView = new UIScrollView(new RectangleF (0, 0, 500, 600)); 

    //set the content size bigger so that it will bounce
    MainScrollView.ContentSize = new SizeF(500,650);

    // initialise and set the refresh class variable 
    refresh = new UIRefreshControl();
    refresh.AddTarget(RefreshEventHandler,UIControlEvent.ValueChanged);
    MainScrollView.AddSubview (refresh);
}

private void RefreshEventHandler (object obj, EventArgs args)
{
    System.Threading.ThreadPool.QueueUserWorkItem ((callback) => {  
        InvokeOnMainThread (delegate() {
        System.Threading.Thread.Sleep (3000);             
                refresh.EndRefreshing ();
        });
    });
}

答案 5 :(得分:2)

对于跳跃问题,Tim Norman's answer解决了这个问题。

如果你使用swift2,这是swift版本:

import UIKit

class NoJumpRefreshScrollView: UIScrollView {

/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func drawRect(rect: CGRect) {
    // Drawing code
}
*/
override var contentInset:UIEdgeInsets {
    willSet {
        if self.tracking {
            let diff = newValue.top - self.contentInset.top;
            var translation = self.panGestureRecognizer.translationInView(self)
            translation.y -= diff * 3.0 / 2.0
            self.panGestureRecognizer.setTranslation(translation, inView: self)
            }
        }
    }
}

答案 6 :(得分:2)

如何在Swift 3中执行此操作:

override func viewDidLoad() {
    super.viewDidLoad()

    let scroll = UIScrollView()
    scroll.isScrollEnabled = true
    view.addSubview(scroll)

    let refreshControl = UIRefreshControl()
    refreshControl.addTarget(self, action: #selector(pullToRefresh(_:)), for: .valueChanged)
    scroll.addSubview(refreshControl)
}

func pullToRefresh(_ refreshControl: UIRefreshControl) {
    // Update your conntent here

    refreshControl.endRefreshing()
}

答案 7 :(得分:1)

我在UIRefreshControl内使UIScrollView正常工作。我继承UIScrollView,阻止更改contentInset并覆盖contentOffset setter:

class ScrollViewForRefreshControl : UIScrollView {
    override var contentOffset : CGPoint {
        get {return super.contentOffset }
        set {
            if newValue.y < -_contentInset.top || _contentInset.top == 0 {
                super.contentOffset = newValue
            }
        }
    }
    private var _contentInset = UIEdgeInsetsZero
    override var contentInset : UIEdgeInsets {
        get { return _contentInset}
        set {
            _contentInset = newValue
            if newValue.top == 0 && contentOffset.y < 0 {
                self.setContentOffset(CGPointZero, animated: true)
            }
        }
    }
}

答案 8 :(得分:0)

对于“跳跃”问题,重写contentInset仅在iOS 9之前解决。 我只是尝试了一种避免跳跃问题的方法:

let scrollView = UIScrollView()
let refresh = UIRefreshControl()
//        scrollView.refreshControl = UIRefreshControl() this will cause the jump issue
refresh.addTarget(self, action: #selector(handleRefreshControl), for: .valueChanged)
scrollView.alwaysBounceVertical = true
//just add refreshControl and send it to back will avoid jump issue
scrollView.addSubview(refresh)
scrollView.sendSubviewToBack(refresh)

可在iOS 9 10 11上运行,依此类推,我希望他们(苹果公司)能解决此问题。

答案 9 :(得分:0)

从iOS 10开始,UIScrollView具有refreshControl属性,您可以将其设置为UIRefreshControl。与往常一样,您不需要管理控件的框架。只需配置控件,为valueChanged事件设置目标动作,然后分配给属性即可。

无论使用的是普通滚动视图,表视图还是集合视图,创建刷新控件的步骤都是相同的。

if #available(iOS 10.0, *) {
  let refreshControl = UIRefreshControl()
  refreshControl.attributedTitle = NSAttributedString(string: "Pull to refresh")
  refreshControl.addTarget(self,
                           action: #selector(refreshOptions(sender:)),
                           for: .valueChanged)
  scrollView.refreshControl = refreshControl
}

@objc private func refreshOptions(sender: UIRefreshControl) {
  // Perform actions to refresh the content
  // ...
  // and then dismiss the control
  sender.endRefreshing()
}

答案 10 :(得分:-3)

您可以简单地创建刷新控件的实例,并将其添加到滚动视图的顶部。然后,在委托方法中,根据您的要求调整其行为。