AFNetWorking3.0 配置https闪退问题

最近在配置https，使用的是AFNetWorking3.0。
一直报个NSArray object nil 闪退，开始找了项目本身的问题，一直找不到。
后来发现，是AFNetWorking里AFSecurityPolicy.m文件中的方法

• (BOOL)evaluateServerTrust:(SecTrustRef)serverTrust forDomain:(NSString *)domain，代码片段里

case AFSSLPinningModeCertificate: {
            NSMutableArray *Certificates = [NSMutableArray array];
            for (NSData *certificateData in self.pinnedCertificates) {
                [Certificates addObject:(__bridge_transfer id)SecCertificateCreateWithData(NULL, (__bridge CFDataRef)certificateData)];
            }
            SecTrustSetAnchorCertificates(serverTrust, (__bridge CFArrayRef)Certificates);

            if (!AFServerTrustIsValid(serverTrust)) {
                return NO;
            }

            // obtain the chain after being validated, which *should* contain the pinned certificate in the last position (if it's the Root CA)
            NSArray *serverCertificates = AFCertificateTrustChainForServerTrust(serverTrust);
            
            for (NSData *trustChainCertificate in [serverCertificates reverseObjectEnumerator]) {
                if ([self.pinnedCertificates containsObject:trustChainCertificate]) {
                    return YES;
                }
            }
            
            return NO;
        }

这句代码获取证书的时候获取不到，数组添加了nil object出现了崩溃
[Certificates addObject:(__bridge_transfer id)SecCertificateCreateWithData(NULL, (__bridge CFDataRef)certificateData)];

解决方法：

1.将后端发过来的.crt证书，修改后缀.cer，导入钥匙串
2.再从钥匙串导出该证书，拉到项目里直接使用