从AppDelegate访问类的运行实例

Question

New to Obj-C, I'm trying to trigger a method myMethod of an instance of viewControllerB. =>viewControllerB is instanciated in viewControllerA. =>I'm trying to call myMethod from the AppDelegate =>It seems that anyway I try to do that, It's triggering myMethod in a new instance of viewControllerB

So the question is: how to send a message to an existing instance of a viewController ?

Please explain with code samples since I'm not yet really comfortable with Obj-C.

Thanks !

viewControllerA.m :

if (_viewControllerB == nil) {
    self.viewControllerB = [[[ViewControllerB alloc] initWithNibName:@"ViewControllerB" bundle:[NSBundle mainBundle]] autorelease];
}

viewControllerB.m :

- (void)myMethod{ NSLog(@"myMethod!"); }

AppDelegate.m : Don't know what tu put here :(

Answer 1

To get same instance

for (UIViewController *view in self.navigationController.viewControllers)

{

if(view isKindOfClass:[viewControllerB class])
{
     [view yourmethodname];
}

}

Answer 2

如果要在viewControllerB的同一实例上调用该函数，则必须从添加它的位置取出该实例。