Can I receive shake events in my AppDelegate?

Question

The application delegate is a UIResponder subclass (since Xcode 4.2), so it should be able to receive touch and motion events. I added this in my AppDelegate class but it is not working:

-(BOOL)canBecomeFirstResponder
{
    return YES;
}

- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event {
    if (motion == UIEventSubtypeMotionShake) {
        NSLog(@"shake");
    }
}

It does work in view controllers of course, but I want to detect shakes application-wide.

Answer 1

Do this:

- (void)applicationDidBecomeActive:(UIApplication *)application
{
    [self becomeFirstResponder];

}
- (void)motionBegan:(UIEventSubtype)motion withEvent:(UIEvent *)event {

    NSLog(@"motionBegan");

}

-(BOOL)canBecomeFirstResponder {
return YES;
}

Answer 2

I extended UIApplication class and added class reference to main: MyApplication.h

@interface MyApplication : UIApplication

@end

MyApplication.m

@implementation MyApplication

- (void) sendEvent:(UIEvent *)event
{
    if( event && (event.subtype==UIEventSubtypeMotionShake))
    {
        AppDelegate *objAppDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate;

        [objAppDelegate doWhatEver];
        [super sendEvent:event];
    }
    else
    {
        [super sendEvent:event];
    }
}

@end

And the last step in main.m

int main(int argc, char *argv[])
{
return UIApplicationMain(argc, argv, NSStringFromClass([MyApplication class]), NSStringFromClass([AppDelegate class]));
}

This works in all cases.

Answer 3

As far as I know, it should need to become the first responder for receiving the event. If your app has UINavigationController or UITabController, maybe you can try to receive it there.