Currently I’m working on yet another Mac app, where I have a NSTabView with multiple tabs that each represent a view controller.
I noticed that when I set my view controller’s title with

self.title = @"some other title"

nothing changes. So I wrote a small NSTabViewItem subclass that updates the title automatically by observing the title key of the view controller.

The code is on github and you can find the important part below.

@implementation GNTabViewItem

-(void)dealloc {
	[self.viewController removeObserver:self forKeyPath:@"title"];

-(void)setViewController:(NSViewController *)viewController {
	[self.viewController removeObserver:self forKeyPath:@"title"];
	[super setViewController:viewController];
	[self.viewController addObserver:self forKeyPath:@"title" options:NSKeyValueObservingOptionNew context:nil];

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
	if([keyPath isEqualToString:@"title"] && object == self.viewController) {
		self.label = self.viewController.title;
	[super observeValueForKeyPath:keyPath ofObject:object change:change context:context];