IOSoss下载文件，获取最后的签名链接不正确

//私有文件处理
         id <ALBBOSSServiceProtocol > ossService = [ALBBOSSServiceProvider getService ];
        [ossService setGlobalDefaultBucketHostId : LLYOSSHostId ];
        [ossService setAuthenticationType :FEDERATION_TOKEN ];
        [ossService setCustomStandardTimeWithEpochSec : self .STSInfo .currenttime .integerValue ];


        [ossService setFederationTokenGetter:^ OSSFederationToken *{
             OSSFederationToken *federationToken = [[ OSSFederationToken alloc ] initWithAk : self .STSInfo .credentials .accesskeyid sk : self .STSInfo .credentials .accesskeysecret tempToken : self .STSInfo .credentials .securitytoken expiration : self .STSInfo .credentials .expiration ];
             return federationToken;
        }];
        
         OSSBucket *bucket = [ossService getBucket: LLYOSSBucketPrivate];
        [bucket setAcl: PRIVATE];
        [bucket setOssHostId: LLYOSSHostId];
//        [bucket setCdnAccelerateHostId:LLYOSScdnAccelerateHostId];
        
         NSString *transString = [downLoadObjectKey stringByReplacingPercentEscapesUsingEncoding :NSUTF8StringEncoding ];
        
         OSSData *ossDownloadData = [ossService getOSSDataWithBucket:bucket key:transString];
         NSString *url = [ossDownloadData getResourceURL : self .STSInfo .credentials .accesskeyid andExpire : LLYOSSTimeAvailable ];
         return url;