// 1.初始化单例类
AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
manager.securityPolicy.SSLPinningMode = AFSSLPinningModeCertificate;
// 2.设置证书模式
NSString * cerPath = [[NSBundle mainBundle] pathForResource:@"xxx" ofType:@"cer"];
NSData * cerData = [NSData dataWithContentsOfFile:cerPath];
manager.securityPolicy = [AFSecurityPolicy policyWithPinningMode:AFSSLPinningModeCertificate withPinnedCertificates:[[NSSet alloc] initWithObjects:cerData, nil]];
manager.securityPolicy.allowInvalidCertificates = NO;
[manager.securityPolicy setValidatesDomainName:YES];