Question

I need access to my core data managed object context often, and instead of getting an instance of the [[UIApplication sharedApplication] delegate] and storing it in a variable every time in every class, I was wondering if it would be ok to do this:

@interface NSObject(DelegateExtension)
- (AppDelegate*)appDelegate;
@end

@implementation 
NSObject(DelegateExtension)
- (AppDelegate*)appDelegate
{
    return (AppDelegate*)[[UIApplication sharedApplication] delegate];
}
@end

so then I can just do self.appDelegate anywhere in my code.

Is anything wrong with doing this that might night be obvious? Is it bad programming practice?

Answer 1

I usually use a global variable to point to the app delegate.

In MyAppDelegate.h:

extern MyAppDelegate* AppDelegate;

In MyAppDelegate.m:

MyAppDelegate* AppDelegate = nil;

- (id)init {
    if (self = [super init]) {
        AppDelegate = self;
        …
    }
}

Now anyone who imports “MyAppDelegate.h” can use the AppDelegate variable to access your app delegate.