looking for current Root View Controller through UIApplication.keyWindow.

getrootvc.m

+ (UIViewController *)getRootViewController {
    
    UIViewController *result = nil;
    
    UIWindow *topWindow = [[UIApplication sharedApplication] keyWindow];
    if (topWindow.windowLevel != UIWindowLevelNormal)
    {
        NSArray *windows = [[UIApplication sharedApplication] windows];
        for(topWindow in windows)
        {
            if (topWindow.windowLevel == UIWindowLevelNormal)
                break;
        }
    }
    
    UIView *rootView = [[topWindow subviews] objectAtIndex:0];
    id nextResponder = [rootView nextResponder];
    
    if ([nextResponder isKindOfClass:[UIViewController class]]) {
        result = nextResponder;
    } else if ([topWindow respondsToSelector:@selector(rootViewController)] 
                && topWindow.rootViewController != nil) {
        result = topWindow.rootViewController;
    } else {
        NSAssert(NO, @"Could not find a root view controller.");
    }
    return result;
}