IOS OSS上传图片出现问题，求助

NSDictionary * alidict1 = [aliDict objectForKey:@"Credentials"];
        NSString * accessKeyId = [alidict1 objectForKey:@"AccessKeyId"];
        NSString * expiration = [alidict1 objectForKey:@"Expiration"];
        NSString * SecurityToken = [alidict1 objectForKey:@"SecurityToken"];
        NSString * accessKeySecret = [alidict1 objectForKey:@"AccessKeySecret"];
        OSSFederationToken * token = [OSSFederationToken new];
        token.tAccessKey = accessKeyId;
        token.tSecretKey = accessKeySecret;
        token.tToken = SecurityToken;
        token.expirationTimeInGMTFormat = expiration;
        NSLog(@"get token:%@",token);
        id<OSSCredentialProvider> credential = [[OSSFederationCredentialProvider alloc]initWithFederationTokenGetter:^OSSFederationToken *{
            return token;
        }];
        NSString *endpoint = ALIYUN_END_POINT;

        OSSClient * client = [[OSSClient alloc] initWithEndpoint:endpoint credentialProvider:credential];
        OSSPutObjectRequest * put = [OSSPutObjectRequest new];
        put.bucketName = ALIYUN_BUCKET;

        put.objectKey = fileName;
        
        NSString * docDir = [self getDocumentDirectory];
        put.uploadingFileURL = [NSURL fileURLWithPath:[docDir stringByAppendingPathComponent:fileName]];
        
        NSLog(@"put.uploadingFileURL:%@",put.uploadingFileURL);
        put.uploadProgress = ^(int64_t bytesSent, int64_t totalByteSent, int64_t totalBytesExpectedToSend) {
            // 当前上传段长度、当前已经上传总长度、一共需要上传的总长度
            NSLog(@"%lld, %lld, %lld", bytesSent, totalByteSent, totalBytesExpectedToSend);
        };
//        put.
        OSSTask * putTask = [client putObject:put];
        [putTask continueWithBlock:^id(OSSTask *task) {
            if (!task.error) {
                NSLog(@"upload object success!");
            }else{
                NSLog(@"upload object failed, error: %@",task.error);
            }
            return nil;
        }];
        [putTask waitUntilFinished];
出现这个问题upload object failed, error: Error Domain=com.aliyun.oss.serverError Code=-403 "(null)" UserInfo={__name=Error, HostId=healthd-user-pic-stage.oss-cn-hangzhou.aliyuncs.com, Message=Access denied by authorizer's policy., Code=AccessDenied, RequestId=56722C6DD4C05B286BEEE823}，这是什么原因呢