Can I use a UIRefreshControl in a UIScrollView?

Solution 1:

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];//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");
        });
    });
}

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.

Solution 2:

Adding to above answers, in some situations you can't set the contentSize (using auto layout perhaps?) or the contentSize's height is less than or equal the height of the UIScrollView. In these cases, the UIRefreshControl won't work because the UIScrollView won't bounce.

To fix this set the property alwaysBounceVertical to TRUE.