经常会用到的两种方式获取当前控制器，一般我们都会把这个方法写在AppDelegate文件里。
1、用tabBarController的时候

//返回当前的VC
- (UIViewController *)getNowViewController
{
    UIViewController *reController = nil;
    //当前用的tabBarController
    if (_tabBarController!=nil)
    {
        UINavigationController  *nav = (UINavigationController *)[[_tabBarController viewControllers] objectAtIndex:_tabBarController.selectedIndex];
        
        UIViewController *topController = [nav topViewController];
        id tempViewController = topController;
        while ([(UIViewController *)tempViewController  presentedViewController]!=nil)
        {
            tempViewController = [(UIViewController *)tempViewController  presentedViewController];
        }
        if (tempViewController!=nil)
        {
            if ([tempViewController isKindOfClass:[UINavigationController class]])
            {
                reController = [(UINavigationController *)tempViewController topViewController];
            }
            else
            {
                reController = tempViewController;
            }
        }
        else
        {
            reController = topController;
        }
    }
    //NSLog(@"getNowViewController is %@....",[reController class]);
    return reController;
}

2、平常的用法

#pragma mark - 获取当前控制器
-(UIViewController *)getCurrentController{

    UIViewController *reController = nil;
    UIWindow *window = [[UIApplication sharedApplication]keyWindow];
    if (window.windowLevel!= UIWindowLevelNormal) {
        NSArray *array = [[UIApplication sharedApplication]windows];
        for (UIWindow *win in array) {
            if (win.windowLevel == UIWindowLevelNormal) {
                window = win;
                break;
            }
        }
    }
    UIView *cuView = [[window subviews]objectAtIndex:0];
    id responder = [cuView nextResponder];
    if ([responder isKindOfClass:[UIViewController class]]) {
        reController = responder;
    }
    else{
        reController = window.rootViewController;
    }
    return reController;
}

3、还有一种情况是用到了UINavigationController但没有用tabBarController。我们在AppDelegate.h文件声明一个UINavigationController的属性，然后在AppDelegate.m文件里实现方法。在使用的时候记得是用self.nav推出控制器！

#pragma mark - 返回当前的控制器
- (UIViewController *)getNowViewController
{
    
    UIViewController *reController = nil;
    //当前用的navController
    
    UINavigationController  *nav = self.nav;
    
    UIViewController *topController = [nav topViewController];
    id tempViewController = topController;
    while ([(UIViewController *)tempViewController  presentedViewController]!=nil)
    {
        tempViewController = [(UIViewController *)tempViewController  presentedViewController];
    }
    if (tempViewController!=nil)
    {
        if ([tempViewController isKindOfClass:[UINavigationController class]])
        {
            reController = [(UINavigationController *)tempViewController topViewController];
        }
        else
        {
            reController = tempViewController;
        }
    }
    else
    {
        reController = topController;
    }
    
    return reController;
}

END.