获取当前的视图控制器或者其视图

- (UIView *)currentView{
    UIViewController *controller = [[[UIApplication sharedApplication] keyWindow] rootViewController];
    
    if ([controller isKindOfClass:[UITabBarController class]]) {
        controller = [(UITabBarController *)controller selectedViewController];
    }
    if([controller isKindOfClass:[UINavigationController class]]) {
        controller = [(UINavigationController *)controller visibleViewController];
    }
    if (!controller) {
        return [UIApplication sharedApplication].keyWindow;
    }
    return controller.view;
}