如何区分当下控制器是 视频控制器 还是 视图控制器 ？

1、首先要知道系统方法是如何控制当前的控制器

//此方法可获取当前显示控制器
 supportedInterfaceOrientations

2、使用runtime中的交换方法
这里主要是替换系统的方法，这样就可以在系统方法中做一些操作，load方法的作用是在程序运行起来将会先加载load方法，加载完成后在加载各个类中的方法

+ (void)load
{
      Method supportedInterfaceOrientations = class_getInstanceMethod(self,@selector(supportedInterfaceOrientations));
      Method wt_supportedInterfaceOrientations = class_getInstanceMethod(self,@selector(wt_supportedInterfaceOrientations));
      method_exchangeImplementations(supportedInterfaceOrientations, wt_supportedInterfaceOrientations);
}

3、处理系统替换之后的方法做一些操作
判断一下，如果是视频控制器的话，就返回上、下、左、右。如果不是视频控制器的话，就返回只能竖屏。

if ([NSStringFromClass(vc.class) isEqualToString: @"ViewController"])
{
     return UIInterfaceOrientationMaskPortrait;
}
else
{
     return UIInterfaceOrientationMaskPortrait | UIInterfaceOrientationMaskLandscapeLeft;
}

4、过滤掉TabBar,navi
这里注意一点通常项目中都会添加TabBar、navi，一般初学者在这里不清楚如何正确的获取当前显示的控制器，主要意思是过滤掉TabBar,navi

- (UIViewController *)getVc:(UIViewController *)vc
{
    if ([vc isKindOfClass: [UITabBarController class]])
    {
        UIViewController *tabBarVC = vc.childViewControllers.firstObject;
        return [self getVc: tabBarVC];
    }
    else if([vc isKindOfClass: [UINavigationController class]])
    {
        UIViewController *navVc = vc.childViewControllers.lastObject;
        return [self getVc: navVc];
    }
    else
    {
        return vc;
    }
}

代码如下：

#import "UIViewController+Extension.h"
#import <objc/message.h>
#import "ViewController.h"
@implementation UIViewController (Extension)

+ (void)load
{
    Method supportedInterfaceOrientations = class_getInstanceMethod(self, @selector(supportedInterfaceOrientations));
    
    Method wt_supportedInterfaceOrientations = class_getInstanceMethod(self, @selector(wt_supportedInterfaceOrientations));
    
    method_exchangeImplementations(supportedInterfaceOrientations, wt_supportedInterfaceOrientations);
}

// 要交换的方法。
- (UIInterfaceOrientationMask)wt_supportedInterfaceOrientations
{
   [self wt_supportedInterfaceOrientations];
    UIViewController *vc = [self getVc: self];
    if ([NSStringFromClass(vc.class) isEqualToString: @"ViewController"])
    {
        return UIInterfaceOrientationMaskPortrait;
    }
    else
    {
        return UIInterfaceOrientationMaskPortrait | UIInterfaceOrientationMaskLandscapeLeft;
    }
}

// 获取当前显示的控制器，主要过滤TabBar,navi
- (UIViewController *)getVc:(UIViewController *)vc
{
    if ([vc isKindOfClass: [UITabBarController class]])
    {
        UIViewController *tabBarVC = vc.childViewControllers.firstObject;
        return [self getVc: tabBarVC];
    }
    else if([vc isKindOfClass: [UINavigationController class]])
    {
        UIViewController *navVc = vc.childViewControllers.lastObject;
        return [self getVc: navVc];
    }
    else
    {
        return vc;
    }
}

@interface UIViewController (Extension)


- (UIInterfaceOrientationMask)wt_supportedInterfaceOrientations;
@end