Exceptions and warnings with CALayer, but I never call them directly

Question

In my app I frequently get the warning

CoreAnimation: warning, deleted thread with uncommitted CATransaction; set CA_DEBUG_TRANSACTIONS=1 in environment to log backtraces.

when I'm transitioning from a View Controller with a MKMapView to a TableViewController. Every once and a while this also throws the following exception:

Terminating app due to uncaught exception 'NSGenericException', reason: '*** Collection <CALayerArray: 0x198e81f0> was mutated while being enumerated.'

My issue is that I never actually call anything from the CoreAnimation library directly in my code so the solution offered here wouldn't work for me.

I can't show you the exact code I'm using for confidentiality reasons, but here is the gist of what my code looks like for the transition:

MKMapView Side

    UITabBarController *tbc = mapViewController.tabBarController;
    UINavigationController *nav = [[tbc viewControllers]objectAtIndex:1];
    ViewController *anotherController = [[nav viewControllers]objectAtIndex:0]; // not the final destination
    [nav popToRootViewControllerAnimated:NO]; // pops to root without animation
    [anotherController setSelectedEvent:event]; // sets which event to select before the segue
    [tbc setSelectedIndex:1]; // changes the selected tab
    [anotherController performSegueWithIdentifier:@"identifier" sender:nil]; // segues to the TableView

Segue from anotherController to tableViewController

if ([[segue identifier]isEqualToString:@"identifier"]) {
        TableViewController *vc = segue.destinationViewController;
        [vc setEvent:selectedEvent];
        [vc.navigationItem setTitle:@"Title"];
        [vc performSelectorInBackground:@selector(searchForAndScrollToEvent:) withObject:_selectedEvent];
}

Final Destination

-(void)searchForAndScrollToEvent:(Events*)event {
    scroll_to_event_waiting_for_table_to_load = YES;
    while (scroll_to_event_waiting_for_table_to_load) {
        usleep(1000);
    }
    NSLog(@"segue completed");
    EventListVirtualTable* virtualTable = [[EventListVirtualTable alloc]initWithViewController:self];
    NSIndexPath *indexPath = [virtualTable indexPathOfEvent:event];

    if (/*indexPath is bad*/) {
        NSLog(@"NOT scrolling to: row %i section %i",indexPath.row,indexPath.section);
        return;
    }

    [self performSelectorOnMainThread:@selector(scrollToAtIndexPath:) withObject:indexPath waitUntilDone:YES];

    while (![[_tableView indexPathsForVisibleRows] containsObject:indexPath]) {
        usleep(100);
    }

    [self performSelectorOnMainThread:@selector(selectCellAtIndexPath:) withObject:indexPath waitUntilDone:YES];
    usleep(delay);
    [self performSelectorOnMainThread:@selector(decselectCellAtIndexPath:) withObject:indexPath waitUntilDone:YES];
}
-(void)scrollToAtIndexPath:(NSIndexPath*)indexPath {
    if(_dataController == nil){return;}
    if (_tableView.numberOfSections == 0 || [self numberOfRowsInSection:indexPath.section] == 0 ) {
        return;
    }
    [_tableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionBottom animated:YES];
    NSLog(@"scrolling to: row %i section %i",indexPath.row,indexPath.section);
}

Thanks everyone for taking the time to offer any responses or useful hints!

score 0 · Accepted Answer · answered Mar 06 '14 at 07:17

Everybody knows not to modify UIView objects from another thread. I was activating UIActivityIndicator from another thread. That was causing the exceptions. I'm still getting the warnings, but the warnings happen now when I cancel threads that I've called.

Exceptions and warnings with CALayer, but I never call them directly

1 Answers1