KKendall KKendall - 1 year ago 52
iOS Question

Can I use a UIRefreshControl in a UIScrollView?

I have about 5

's already in my app which all load multiple
files. We now want to use a
. They are built to be used with UITableViewControllers (per UIRefreshControl class reference). I do not want to re-do how all 5
work. I have already tried to use the
in my
's, and it works as expected except for a few things.

  1. Just after the refresh image turns into the loader, the
    jumps down about 10 pixels, which only does not happen when I am very careful to drag the
    down very slowly.

  2. When I scroll down and initiate the reload, then let go of the
    , the
    stays where I let it go. After it is finished reloading, the
    jumps up to the top with no animation.

Here is my code:

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];

Is there any way I can save a bunch of time and use a
in a

Thank You!!!

Answer Source

I got a UIRefreshControl to work with a 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];

        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");

Need to do the data update on a separate thread or it will lock up the main thread (which the UI uses to update the UI). So while the main thread is busy updating the data, the UI is also locked up or frozen and you never see the smooth animations or spinner.

EDIT: ok, I'm doing the same thing as OP and i've now added some text to it (ie, "Pull to Refresh") and it does need to get back onto the main thread to update that text.

Updated answer.