即获取当前显示的控制器

适用Swift 3.0（此段写于 2016/12/15）

给UIViewController建了分类

class func currentViewController() -> UIViewController {
        let vc = UIApplication.shared.keyWindow?.rootViewController
        return UIViewController.findBestViewController(vc: vc!)
    }
private class func findBestViewController(vc : UIViewController) -> UIViewController {
        
        if vc.presentedViewController != nil {
            return UIViewController.findBestViewController(vc: vc.presentedViewController!)
        } else if vc.isKind(of:UISplitViewController.self) {
            let svc = vc as! UISplitViewController
            if svc.viewControllers.count > 0 {
                return UIViewController.findBestViewController(vc: svc.viewControllers.last!)
            } else {
                return vc
            }
        } else if vc.isKind(of: UINavigationController.self) {
            let nvc = vc as! UINavigationController
            if nvc.viewControllers.count > 0 {
                return UIViewController.findBestViewController(vc: nvc.topViewController!)
            } else {
                return vc
            }
        } else if vc.isKind(of: UITabBarController.self) {
            let tvc = vc as! UITabBarController
            if (tvc.viewControllers?.count)! > 0 {
                return UIViewController.findBestViewController(vc: tvc.selectedViewController!)
            } else {
                return vc
            }
        } else {
            return vc
        }
    }

在外部调用UIView.currentViewController即可，打印结果:

你是什么颜色 阴婷就是什么脸色

简单粗暴的直接获取控制器类名需要type函数：type(of: UIViewController.currentViewController().self)打印结果：

努力一定会成攻

对应OC版本（同样是建了分类）：

+(UIViewController*)findBestViewController:(UIViewController*)vc
{
    if (vc.presentedViewController) {
        return [UIViewController findBestViewController:vc.presentedViewController];
    } else if ([vc isKindOfClass:[UISplitViewController class]])
    {
        UISplitViewController* svc = (UISplitViewController*)vc;
        if (svc.viewControllers.count > 0) {
            return [UIViewController findBestViewController:svc.viewControllers.lastObject];
        } else {
            return vc;
        }
    } else if ([vc isKindOfClass:[UINavigationController class]])
    {
        UINavigationController* nvc = (UINavigationController*)vc;
        if (nvc.viewControllers.count > 0) {
            return [UIViewController findBestViewController:nvc.topViewController];
        } else {
            return vc;
        }
    } else if ([vc isKindOfClass:[UITabBarController class]])
    {
        UITabBarController* tvc = (UITabBarController*)vc;
        if (tvc.viewControllers.count) {
            return [UIViewController findBestViewController:tvc.selectedViewController];
        } else {
            return vc;
        }
    } else {
        return vc;
    }
}

+(UIViewController *)currentViewController
{
    UIViewController* viewController = [UIApplication sharedApplication].keyWindow.rootViewController;
    return [UIViewController findBestViewController:viewController];
}