AFNetworking编译报错 Property with 'retain (or strong)' attribute must be of object type

AFNetworking 2.0 当Deployment Target 低于6.0时，AFURLConnectionOperation.h,AFURLSessionManager.h

@property (nonatomic, strong) dispatch_queue_t completionQueue;

由于sdk低于6.0时，dispatch_queue_t  ARC没有托管，出现提示错误

Property with 'retain (or strong)' attribute must be of object type

修改为

#if OS_OBJECT_USE_OBJC

@property (nonatomic, strong) dispatch_queue_t completionQueue;

#else

@property (nonatomic, assign) dispatch_queue_t completionQueue;

#endif

/**

 The dispatch group for `completionBlock`. If `NULL` (default), a private dispatch group is used.

 */

#if OS_OBJECT_USE_OBJC

@property (nonatomic, strong) dispatch_group_t completionGroup;

#else

@property (nonatomic, assign) dispatch_group_t completionGroup;

#endif