最新版 AFNetworing 如何允许自建证书通过？

AFHTTPRequestOperationManager *manager = [[AFHTTPRequestOperationManager alloc] initWithBaseURL:baseURL];
manager.responseSerializer = [AFJSONResponseSerializer serializer];
manager.requestSerializer = [AFHTTPRequestSerializer serializer];
manager.requestSerializer.timeoutInterval = 10;
manager.securityPolicy.allowInvalidCertificates = YES;
manager.responseSerializer.acceptableContentTypes =[NSSet setWithObjects:@"text/html", @"text/plain",nil];
manager.securityPolicy.allowInvalidCertificates = YES;
manager.securityPolicy.validatesDomainName = NO;

设置了以上代码并没有卵用，请问如何解决这个问题？一直报
error:Error Domain=NSCocoaErrorDomain Code=3840 "The operation couldn ’ t be completed. (Cocoa error 3840.)" (JSON text did not start with array or object and option to allow fragments not set.) UserInfo=0x7fbf6a48a850 {NSDebugDescription=JSON text did not start with array or object and option to allow fragments not set.}