Custom activity view is garbled when portrait/landscape mode gets changed

[thorar]

A strang behaviour occurs using custom activities.

I set a custom activity view (UIProgressView). Using the demo App, I wrapped the ViewController of the demo code in a UINavigationController

    UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:self.viewController];
    self.window.rootViewController = navigationController;

and modified the ViewController as follows.

- (void)viewDidLoad
{
    [super viewDidLoad];

    UIProgressView *progressView = [[UIProgressView alloc] initWithFrame:CGRectMake(0, 0, 200, 20)];
    progressView.progress = 0.5;

    refreshControl = [[ODRefreshControl alloc] initInScrollView:self.tableView activityIndicatorView:progressView];
    [refreshControl addTarget:self action:@selector(dropViewDidBeginRefreshing:) forControlEvents:UIControlEventValueChanged];

    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh target:self action:@selector(doRefresh)];
}

- (void)doRefresh {
    [refreshControl beginRefreshing];
    [self.tableView setContentOffset:CGPointMake(0, -44) animated:YES];
    [self dropViewDidBeginRefreshing:refreshControl];
}

I perform one refresh in portrait, rotate to landscape and perform a second refresh. I get several copies of the UIProgressView drawn. The same happens if I start on landscape and then turn to portrait.