Question

Let me provide some context: I am building a tabbed application that allows a user to find and view some videos hosted on our server. Each tab has the videos grouped in a different manner with a segmented control in the navigation bar that a user can use to sort the list even more precisely (by title, date, etc…). Upon hitting “Sort” in the segmented control, a modal view controller is presented with the options available on a particular tab. An option is chosen and the choice is relayed back to parent view controller, which calls on the server for a sorted list.

Now here is the problem: On iOS 4.2, which we would like to support, the modal view either crashes after a sort option has been chosen, or it dismisses and then immediately reappears one more time. If it reappears, it only does so once and does NOT loop indefinitely. I know it has something to do with the transition and the view’s life cycle but I can’t seem to get this just right.

Code:

The parent view

-(void) segmentAction:(id)sender{
    //create a sort view and pass it a value that indicates what the options should be
    ModalSortViewController *sortView = [[ModalSortViewController alloc]    
                                        initWithNibName:nil bundle:nil sortByView:0];
    [sortView setDelegate:self];
    [sortView setModalTransitionStyle:UIModalTransitionStylePartialCurl];
    [sortView setModalPresentationStyle:UIModalPresentationFormSheet];
    [self presentModalViewController:sortView animated:YES];
}

-(void) refresh:(id)sender{
    [self fetchEntries];
}

//Delegate protocol for all tabbed table views
//Receives buttonIndex from the modal sort view
-(void)sortByButtonIndex:(int)buttonIndex{

    if(buttonIndex==1){
        //If sorting by title
        fetchURL = @"fakeURL.com/?method=iGetCategories&sortBy=category&sortByOrder=ASC";
        [self fetchEntries];
    }
    else if (buttonIndex==2){
        //If sorting by number of items
        fetchURL = @"fakeURL.com/?method=iGetCategories&sortBy=count&sortByOrder=DESC";
        [self fetchEntries];
    }
    else if(buttonIndex==0){
        //Resets sort selection to nothing
        segmentedControl.selectedSegmentIndex = -1;
    }
    [self dismissModalViewControllerAnimated:YES];
}

The modal view

@synthesize delegate, option1, option2;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil sortByView:(int)_viewInt
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
        sortChosen = 0;
        viewInt = _viewInt;
    }
    return self;
}

//This method is called whenever a selection on the modal view has been made.
//The button tags have been set in IB and are sent to the parent table view controller
//where a switch statement is in place to sort its data by the selection.
-(IBAction)madeSelection:(id)sender{
    sortChosen = [sender tag];
    [self.delegate sortByButtonIndex:sortChosen];
}

-(void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];//Added after Felix pointed out that the super was not called
    switch (viewInt) {
        case CAT_FOLDERS:
            [self.option1 setTitle:@"By Category Name" forState:UIControlStateNormal];
            [self.option2 setTitle:@"By Number of Items" forState:UIControlStateNormal];
            break;

        case PRES_FOLDERS:
            [self.option1 setTitle:@"By Presenter Name" forState:UIControlStateNormal];
            [self.option2 setTitle:@"By Number of Items" forState:UIControlStateNormal];
            break;

        case MEDIA:
            [self.option1 setTitle:@"By Media Title" forState:UIControlStateNormal];
            [self.option2 setTitle:@"By Release Date" forState:UIControlStateNormal];
            break;

        default:
            break;
    }
}

Crash Results:

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException',
reason: 'Attempting to begin a modal transition from <UINavigationController: 
0x139160> to <ModalSortViewController: 0x172810> while a transition is already in
progress. Wait for viewDidAppear/viewDidDisappear to know the current transition has completed'

Sorry about the length. I wanted to be as clear and thorough as possible. Thank you in advance!

EDIT: I should mention that the crashing/repeat appearing seems to be dependent on where sortByButtonIndex: is called and when the view is dismissed.

Answer 1

Figures I would solve this hours after I posted a bounty on it!

The problem was that the fetchEntries method, which I did not post because I didn’t think it was the culprit, sets my segmented control’s selected index to -1 when it completes its call to the server. It appears that newer versions of iOS ignore the the EventValueChanged if it is changing to -1. I simply set a condition to ignore a -1 index on the segmented control in segmentAction: method and it works.

-(void) segmentAction:(id)sender{

    if(segmentedControl.selectedIndex != -1){
        //create a sort view and pass it a value that indicates what the options should be
        ModalSortViewController *sortView = [[ModalSortViewController alloc]    
                                        initWithNibName:nil bundle:nil sortByView:0];
        [sortView setDelegate:self];
        [sortView setModalTransitionStyle:UIModalTransitionStylePartialCurl];
        [sortView setModalPresentationStyle:UIModalPresentationFormSheet];
        [self presentModalViewController:sortView animated:YES];
    }

}