Crappy iOS APIs – UINavigationController

While Apple has some great products and has achieved excellence designing beautiful UIs, the same can’t be said for many of its APIs. Anyone who has tried to do even the simplest of the things just by looking at the documentation or based on assumptions of how one could expect that a given thing would work based on context and method names, would know what I am talking about: literally hours trying to correctly setup a more complex UILabel, or pulling the hair out of the head after not being able to easily change the color of an UINavigationController or UIToolBar. The list goes on ad-infinitum.

Take UINavigationController for instance: it has methods to set the title, the left and right buttons, and for the back button when a new controller is pushed into the stack. So imagine you are in controller A,which pushes controller B¬†into the stack by calling [self.navigationController pushViewController:b animated:YES]. The view slides left with a nice looking animation, and b’s view pops in the screen. By default, iOS will automatically set up a working back button for you – which is great – and that button’s label is set to the previous screen’s title – that, again, makes a lot of sense.

However, if for any reason you’d like to change the label of the back button to another text. you can’t just do

self.navigationItem.backBarButtonItem.title = @"Back";

on b. Well, you can, but it won’t work. It does not crash the app, but also does nothing. Now imagine for a moment that doing the previous code is the most natural thing anyone could possible do, but it does not work. “Ok then, maybe if I override the entire button”:

self.navigationItem.backBarButtonItem = [[[UIBarButtonItem alloc] initWithTitle:@"Back"
	style:UIBarButtonItemStyleBordered target:nil action:nil] autorelease];

only that it also does not work: you’d still get the default button, despite assigning a new one. Lots of tries here and there, and you finally figure out (by looking a Google or deciphering the poorly written documentation) that the only way to get it working is to set the title BEFORE you push b into the stack, in the PREVIOUS controller. In other words, you must the the title you’d like to see in b in the a¬†controller. Genius, right?! Apple just killed SoC. It will look like this:

// Somewhere in AController
BController *b = [[BController alloc] init];
self.title = @"Back"; // Scream in pain
self.navigationItem.back
[self.navigationController pushViewController:b animated:YES];
[b release];

There simply can’t be any good reason on earth to do that. It get’s worse then you need to have a custom method called before the view pops out of the stack, as it is not possible to override backButton‘s selector.

So that one should do, instead? Well, what I do is the following: I force backButton to be hidden when the new controller slides up on the screen, and then set up a “left” button:

// BController
-(void) viewDidLoad {
	self.navigationItem.hidesBackButton = YES; // Important
	self.navigationItem.leftBarButtonItem = [[[UIBarButtonItem alloc] initWithTitle:@"Back"
		style:UIBarButtonItemStyleBordered target:self action:@selector(myCustomBack)] autorelease];
}

-(void) myCustomBack {
	// Some anything you need to do before leaving
	[self.navigationController popViewControllerAnimated:YES];
}

it just works. It’s a lot of work, of course, but works. Now, if you’d like to have a different layout for such button, that’s a whole new story.