AFNetworking 中Assigning to 'AFSSLPinningMode' from incompatible type 'unsigned long _Nullable'

手动导入AFNetworing 出现上边错误

解决方法：

1）AFSecurityPolicy.m

self.SSLPinningMode =  [[decoder decodeObjectOfClass:[NSNumber class] forKey:NSStringFromSelector(@selector(SSLPinningMode))] unsignedIntegerValue];
改为
self.SSLPinningMode = (AFSSLPinningMode)  [[decoder decodeObjectOfClass:[NSNumber class] forKey:NSStringFromSelector(@selector(SSLPinningMode))] unsignedIntegerValue];
           

2）AFNetworkReachability.m

_networkReachability = CFRetain(reachability);

 改为

 _networkReachability = (SCNetworkReachabilityRef)CFRetain(reachability);


           

3）添加依赖库，去除其他错误

Security.framework
MobileCoreServices.framework
SystemConfiguration.framework
           

问题：

为啥我新建工程，就没有出现上边错误呢？