Short hand for [[UIApplication sharedApplication] delegate]?

Question

I stored global variables in my AppDelegate and access them by:

AppDelegate *d = [[UIApplication sharedApplication] delegate];
d.someString = ...

What's the recommend way to save some typing and so I don't need to AppDelegate *d = [[UIApplication sharedApplication] delegate]; again and again? Thanks!

import your AppDelege into your pch file. By doing this you don't need to import in every file and you can get this macro anywhere across your project. — Ans, Nov 23 '13 at 10:38
Note that if you find yourself typing `AppDelegate *d = [[UIApplication sharedApplication] delegate];` again and again, that might be a code smell. Do you really need the app delegate for app-delegate-ish things, or are you using it as a dumping ground for global state? — Kristopher Johnson, Nov 27 '13 at 18:58

score 41 · Accepted Answer · edited Nov 10 '10 at 06:46

41

As Shaggy Frog said, define a macro in your YourAppDelegate.h file, an example like this:

#define AppDelegate (YourAppDelegate *)[[UIApplication sharedApplication] delegate]

Then you can get the app delegate in your code like this:

[AppDelegate ......];

edited Nov 10 '10 at 06:46

Adam Eberbach

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answered Nov 10 '10 at 04:24

Nevin

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2

This. This is the best solution. – Adam Ernst Nov 10 '10 at 04:38
1

Don't you need to wrap it in parenthesis like this: http://stackoverflow.com/questions/4549410/define-the-app-delegate-as-a-constant]? – ari gold Apr 30 '13 at 06:10
Also, make sure that "AppDelegate" and "YourAppDelegate" are different words. Sometimes "YourAppDelegate", that is the name of your app delegate defaults to simply "AppDelegate". – ari gold Apr 30 '13 at 06:14

score 11 · Answer 2 · answered Nov 10 '10 at 03:51

Since your app delegate never really changes, you can create an external that you define in the app delegate code, very similar to the NSApp external for Mac OS X Cocoa applications.

So, define the external in your AppDelegate header (or something else that you would include everywhere):

extern AppDelegate* appDelegate;

Then create it and set it in your implementation file:

AppDelegate* appDelegate = nil;

// later -- i can't recall the actual method name, but you get the idea
- (BOOL)applicationDidFinishLaunchingWithOptions:(NSDictionary*)options
{
  appDelegate = self;
  // do other stuff
  return YES;
}

Then other classes can just access it:

#import "AppDelegate.h"

// later
- (void)doSomethingGreat
{
  NSDictionary* mySettings = [appDelegate settings];
  if( [[mySettings objectForKey:@"stupidOptionSet"] boolValue] ) {
    // do something stupid
  }
}

I prefer this solution as the dot notation accessors worked with this solution — Rob, Apr 28 '11 at 02:15

score 8 · Answer 3 · answered Nov 10 '10 at 03:52

8

You could just create a C-style macro and put it in a header file somewhere.

(As for using your app delegate as a giant global variable catch-all, that's another rant for another day.)

answered Nov 10 '10 at 03:52

Shaggy Frog

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score 4 · Answer 4 · answered Nov 10 '10 at 04:01

I create a category called UIApplication+delegate with some convenience messages in it. Getting my specific delegate being one of the convenience messages. So, for instance, if my app delegate was called MyAppDelegate, it would look like this:

UIApplication+delegate.h

#import "MyAppDelegate.h"

@interface UIApplication(delegate)
+ (MyAppDelegate *)thisApp;
@end

and UIApplication+delegate.m

#import "UIApplication+delegate.h"


@implementation UIApplication(delegate)

+ (MyAppDelegate *)thisApp {
    return (MyAppDelegate*)[[UIApplication sharedApplication] delegate];
}

@end

In a class that needs the delegate, I do this:

#import "UIApplication+delegate.h"

...

- (void)doStuff {
    MyAppDelegate *app = [UIApplication thisApp];
    // use "app"
}

score 2 · Answer 5 · answered Nov 10 '10 at 04:39

I also created a category, except that I applied mine to NSObject so any object in the application can easily get to the delegate.

#import "MyAppDelegate.h"

@interface NSObject(delegate)
- (MyAppDelegate *) appDelegate;
@end

#import "NSObject+delegate.h"

@implementation UIApplication(delegate)

- (MyAppDelegate *)appDelegate {
    return (MyAppDelegate *)[[UIApplication sharedApplication] delegate];
}

@end

Short hand for [[UIApplication sharedApplication] delegate]?

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