从app delegate调用视图控制器方法

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 {
     [..]
}

Answer 1

I would try

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

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

Answer 2

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.

Answer 3

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.

Answer 4

在Swift中，你可以这样写

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

Answer 5

Try to write

 -(void) myMethodHere;

in MainViewController.h