Question

I was wondering if someone could explain this to me. I’m building a universal app using storyboards. The iPhone version has a navigation controller with a master list view and then a sub-list view (both are tableview controllers.

The iPad app uses a split view controller to achieve the same thing as the iphone (a master list, with a detail list). All is good, however when using the “replace” segue to transition to a new detail view on the split view controller I have to embed the new detail views within their own navigation controller, whereas I don’t need to do this on the iphone (it’s already within a navigation controller. (Hopefully this makes some sense)

My code (which works) ends up looking like so:

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    NotesListViewController *listNotesView;
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad) {
        listNotesView = [[segue destinationViewController] topViewController];
    } else {
        listNotesView = [segue destinationViewController];
    }

    if ([segue.identifier isEqualToString:@"NotesByDate"]) {
        [listNotesView setGroupType:@"date"];
    } else if ([segue.identifier isEqualToString:@"NotesByTopic"]) {
        [listNotesView setGroupType:@"topics"];
    } else if ([segue.identifier isEqualToString:@"NotesBySpeaker"]) {
        [listNotesView setGroupType:@"speaker"];
    }

So… The issue is that the first condition of the IF statement is generating a warning (incompatible pointer type assigning to NoteListViewController from UIViewController). However, it isn’t a UIViewController, it’s a UITableViewController. On the iPhone version it WOULD be a UIView, but I’m specifically checking for iPad here.

Like I said, it works, so maybe this isn’t really an issue, but I’m a bit annoyed by the warning constantly appearing and being unsure of how/if I can fix it.

I’ll try to post images of the storyboards in a bit, hopefully that helps explain this some.

Answer 1

All you have to do is typecast the UIViewController you retrieve with [[segue destinationViewController] topViewController] to a NotesListViewController.

So, you would have listNotesView = (NotesListViewController *)[[segue destinationViewController] topViewController];

As an aside, the reason your code works but generates a warning is because regardless of what type you call an object, the actual type that is pointed to in memory is what matters(You can declare something as an NSString and allocate the memory with [NSDictionary alloc], but that would just lead to confusion). -topViewController returns a UIViewController object because somewhere along the line, any class it returns will inherit from UIViewController, like your NotesListViewController does, but it doesn’t have enough information to be any more specific than that, so you have to give the compiler the extra information by typecasting the object.