UIViewController -viewDidLoad not being called

Question

Being new to Cocoa, I'm having a few issues with Interface Builder, UIViewController and friends.

I have a UIViewController subclass with a UIView defined in a xib, and with the controller's view outlet connected to the view. The xib's "file's owner" is set as myViewcontroller subclass.

In this one instance, the following code to load the controller/view (from the main view controller) doesn't work as expected:

if ( self.myViewController == nil )
{
    self.myViewController = [[MyViewController alloc]
        initWithNibName:@"MyViewController" bundle:nil];
}

[self.navigationController 
    pushViewController:self.myViewController animated:YES];

In MyViewController's methods, I have placed breakpoints and log messages to see what is going on:

-(id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {

    if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) {
        NSLog(@"initWithNibName\n");
    }

    return self;
}

-(void)viewDidLoad {

    [super viewDidLoad];
    NSLog(@"viewDidLoad\n");
}

Expected result

Both -initWithNibName and -viewDidLoad methods are called, and myViewController's view is displayed.

Observed result

Only -initWithNibName is called, the view is not displayed.

Have I missed something? Can anyone recommend anything to check? (Particularly in the wondrously opaque Interface Builder tool).

Solution 1

Ok, I have a partial answer - maybe the gurus can explain some more. The problem is:

[self.navigationController pushViewController:myViewController animated:YES];

Looking more closely, in this case self.navigationController is nil - so the push message is going no-where.

Instead, if I send:

[self.view addSubview:self.myViewController.view];

Then the view appears and -viewDidLoad is called.

I'm not entirely sure why self.navigationController is not set in this instance - the only thing I can think of is that self is a subclass of UIViewController rather than UITableViewController (where the pushViewController code came from).

Also, silently allowing messages to go to nil seems like a bad idea, although these answers say otherwise. See also my question here.

Final edit:

Answers in comments below, I've realised the display function that I was actually after (given myViewController is modal) is:

[self presentModalViewController:myViewController animated:YES];

Thanks everyone for their helpful responses.

Solution 2

RE: SOLUTION FOUND!!!!!

Indeed that seems to be a working solution, however the real trick is not in setting the view.hidden property to NO, what makes the view load from the nib file is the calling of the UIViewController's view method, the view only actually gets loaded from the nib when the view method is called for the first time.

In that sense, a simple [viewController view] message would force the view to load from the nib file.

Solution 3

SOLUTION FOUND!!!!!

Even something as innocuous as this makes the viewDidLoad method call happen.

Insert this right after alloc initWithNibName

viewController.view.hidden = NO; //calls viewDidLoad

Solution 4

make sure that the view outlet in File's Owner (your viewController subclass) is connected to the actual view (i.e. the 480X320 canvas you see on your screen that you use to build your UI)

Solution 5

Chances are that you might not have linked the supposed ViewController in main.storyboard from the Identity Inspector to the custom class you created. You might be able to navigate to that controller from other view controllers via segues but any of viewDidLoad(), viewWillAppear() etc. won't be executed.

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