获取任意ViewController的UINavigationC

在一个demo中学到的, 以前没找到, 分享出来供大家学习

获取任意ViewController的navigationController

```

@implementation UIViewController (IMYPublic)

- (UINavigationController*)imy_navigationController

{

UINavigationController* nav = nil;

if ([self isKindOfClass:[UINavigationController class]]) {

nav = (id)self;

}

else {

if ([self isKindOfClass:[UITabBarController class]]) {

nav = [((UITabBarController*)self).selectedViewController imy_navigationController];

}

else {

nav = self.navigationController;

}

}

return nav;

}

@end

```