#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 100000 //假如固件是iOS10 控制器self就遵守CAAnimationDelegate协议
@interface ViewController ( ) <CAAnimationDelegate>
#else //固件低于iOS 10, 否则就不遵守CAAnimationDelegate协议 无需填写
@interface ViewController ( )
#endif

#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 100000 //假如固件是iOS10 控制器self就遵守CAAnimationDelegate协议
@interface ViewController ( ) <CAAnimationDelegate>
#else //固件低于iOS 10, 否则就不遵守CAAnimationDelegate协议 无需填写
@interface ViewController ( )
#endif