Calling view controller method from app delegate

Question

I'm trying to call a method in the view controller from the app delegate, but Xcode says No known class method for selector 'myMethodHere'. Here's my code:

AppDelegate.m:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    [..]
            [MainViewController myMethodHere];
    [..]
    return YES;
}

MainViewController.m:

-(void) myMethodHere {
     [..]
}

score 13 · Accepted Answer · answered Nov 15 '11 at 18:39

13

I would try

MainViewController * vc = [[MainViewController alloc]init];
[vc myMethodHere];
[vc release];

Make sure to import your MainViewController in your app delegate .m file
make sure you add "myMethodHere" to your MainViewController .h file

answered Nov 15 '11 at 18:39

Louie

5,920
5
31
45

4

Im not too sure if this works though. Doesn't this create another instance of the view you are trying to access? Lets say you are trying to run a method in that view controller, but the method is dependant on a certain bit of UI/data in that view, then doing this won't work, as the instance you have created does not contain that data right?? – Supertecnoboff Mar 26 '16 at 16:35

score 11 · Answer 2 · answered Nov 15 '11 at 18:40

You are trying to call a class method when you want to call an instance method. If the view controller is the root view controller, then you should be able to call it thus:

UIWindow *window = [UIApplication sharedApplication].keyWindow;
MainViewController *rootViewController = window.rootViewController;
[rootViewController myMethodHere];

If it's not the root view controller then you'll have to find some other way of getting hold of the instance and then calling the method as in the last line above.

score 7 · Answer 3 · answered Nov 17 '12 at 15:20

If you want to access to a view controller on a story board, you may use this block of code from the AppDelegate:

MainViewController *rootViewController = (MainViewController*)self.window.rootViewController;
[rootViewController aMethod];

Remember to add the import.

score 2 · Answer 4 · answered Oct 03 '15 at 23:23

2

In Swift, you can write it like this

    UIApplication.sharedApplication().keyWindow?.rootViewController?.yourMethodName()

answered Oct 03 '15 at 23:23

Sruit A.Suk

7,073
7
61
71

score 0 · Answer 5 · answered Nov 15 '11 at 18:38

0

Try to write

 -(void) myMethodHere;

in MainViewController.h

answered Nov 15 '11 at 18:38

Manlio

10,768
9
50
79

Calling view controller method from app delegate

5 Answers5