iOS 6 appearance when contained in multiple classe

问题:

I’m using the appearanceWhenContainedIn method on certain UI elements that I want to customise in my iOS 6 app. The problem I found is that none of my customisations are applied if I try to provide more than one container class, like so:

// Works neither for toolbar nor navbar items
[UIBarButtonItem appearanceWhenContainedIn:[UINavigationBar class], [UIToolbar class], nil]

// Works fine (but only for navbar items, obviously)
[UIBarButtonItem appearanceWhenContainedIn:[UINavigationBar class], nil]

The official docs say that the parameter for this method can be a nil-terminated list of multiple classes, but in my case it never works the way it should. Am I missing something here?

回答1:

From the docs:

appearanceWhenContainedIn:

...

The appearance proxy for the receiver in a given containment hierarchy.

That actually means that nil-terminated list defines not the list of the container classes for UIBarButtonItem, but container hierarchy from top to bottom, so

[UIBarButtonItem appearanceWhenContainedIn:[UINavigationBar class], [UIToolbar class], nil]

returns appearance proxy for UIBarButtonItem that is inside UINavigationBar, and UINavigationBar in turn is inside UIToolbar.

or

[[UIBarButtonItem appearanceWhenContainedIn:[UIToolbar class],[ViewController class], nil] setTintColor:[UIColor redColor]];

set red tint color for UIBarButtonItems that are in any UIToolBar which are in ViewController class.

So to set appearance for UINavigationBar and UIToolBar separately you'll need 2 separate calls to the +appearanceWhenContainedIn: method