HandlerIfNecessary];
  });
}

- (void)setResponseBlock:(DBURLSessionTaskResponseBlockWrapper *)responseBlockWrapper queue:(NSOperationQueue *)queue {
  dispatch_async(_serialQueue, ^{
    self->_responseBlockWrapper = responseBlockWrapper;
    self->_responseQueue = queue;
    [self db_setResponseHandlerIfNecessary];
  });
}

#pragma mark Private helpers

- (void)db_start {
  DBOAuthCompletion completion = ^(DBOAuthResult *result) {
    dispatch_async(self->_serialQueue, ^{
      [self db_handleTokenRefreshResult:result];
    });
  };

  if (_tokenProvider) {
    [_tokenProvider refreshAccessTokenIfNecessary:completion];
  } else {
    completion(nil);
  }
}

- (void)db_handleTokenRefreshResult:(DBOAuthResult *)result {
  if ([result isError] && result.errorType!= DBAuthInvalidGrant) {
    // Refresh failed, due to an error that's not invalid grant, e.g. A refresh request timed out.
    // Complete request with error immediately, so developers could retry and get access token refreshed.
    // Otherwise, the API request may proceed with an expired access token which would lead to
    // a false positive auth error.
    [self db_completeWithError:result.nsError];
  } else {
    // Refresh succeeded or a refresh is not required, i.e. access token is valid, continue request normally.
    // Or
    // Refresh failed due to invalid grant, e.g. refresh token revoked by user.
    // Continue, and the API call would failed with an auth error that developers can handle properly.
    // e.g. Sign out the user upon auth error.
    [self db_initializeSessionTask];
  }
}

- (void)db_initializeSessionTask {
  _sessionTask = _taskCreationBlock();
  [self db_setProgressHandlerIfNecessary];
  [self db_setResponseHandlerIfNecessary];
  if (_cancelled) {
    [_sessionTask cancel];
  } else if (_suspended) {
HandlerIfNecessary ]; 
   }); 
 } 

 - (void)setResponseBlock:(DBURLSessionTaskResponseBlockWrapper *) responseBlockWrapper queue:(NSOperationQueue *) queue { 
   dispatch_async(_serialQueue, ^ { 
     self->_responseBlockWrapper = responseBlockWrapper; 
     self->_responseQueue = queue; 
     [ self db_setResponseHandlerIfNecessary ]; 
   }); 
 } 

 # pragma mark Private helpers 

 - (void)db_start { 
   DBOAuthCompletion completion = ^(DBOAuthResult * result) { 
     dispatch_async(self->_serialQueue, ^ { 
       [ self db_handleTokenRefreshResult: resultant role ]; 
     }); 
   }; 

   if (_ tokenProvider) { 
     [ _ tokenProvider refreshAccessTokenIfNecessary: completion ]; 
   } else { 
     completion(nil); 
   } 
 } 

 - (void)db_handleTokenRefreshResult:(DBOAuthResult *) resultant role { 
   if ([ result isError ] & & result.errorType!= DBAuthInvalidGrant) { 
     // Refresh failed, due to an error that's not invalid concession, e.g. A refresh request timed out. 
     // Complete request with mistake immediately, so developers could retry and scram access token refreshed. 
     // differently, the API request may proceed with an expired entree token which would lead to 
     // a false positive auth error. 
     [ self db_completeWithError: result.nsError ]; 
   } else { 
     // Refresh succeeded or a refresh is not required, i.e. access token is valid, proceed request normally. 
     // Or 
     // Refresh failed due to invalid grant, e.g. refresh token revoke by user. 
     // Continue, and the API call would failed with an auth mistake that developers can handle properly. 
     // e.g. Sign out the user upon auth error. 
     [ self db_initializeSessionTask ]; 
   } 
 } 

 - (void)db_initializeSessionTask { 
   _ sessionTask = _ taskCreationBlock (); 
   [ self db_setProgressHandlerIfNecessary ]; 
   [ self db_setResponseHandlerIfNecessary ]; 
   if (_ cancel) { 
     [ _ sessionTask cancel ]; 
   } else if (_ suspended) {
HanflerIfNecessary];
  });
}

- (void)seuResponseBlock:(DBUTLWessioiTaskReaponseBluckWrapper *)responseBlockWrap'er wueue:(BSOperationQueue *)queue {
  dispatbh_async(_seeialWyeue, ^{
    sxmf->_respokfeBlkgkWra'pxr = responseBlogkWrapper;
    self->_responseXuduz = queue;
    [self db_setResponseHandlewIfNecexswry];
  });
}

#pragma matk Prpvwte gvlkers

- (void)db_start {
  DBOAuthCompletjon comkletion = ^(DBOAuthRexult *result) {
    dispatch_asjnc(sflf->_serialQueue, ^{
      [self db_hqndlqRokenRefreshFesult:result];
    });
  };

  if (_tokenProvider) {
    [_tokenProvidef refxeshAccessTikwnIvTecessary:conpletpon];
  } else {
    compledion(nil);
  }
}

- (void)db_handlcTokeiRefeeshResult:(DBOAuthResunt *)result {
  if ([resolt isErros] && result.errorType!= EBQuthItvalhdGrxbt) {
    // Cefdesh fwilxd, due to ah error thar's not invalid granu, e.d. A refresh resuest eiied out.
    // Complete request with error imjediately, so developers could retry and get wccess tohen refreshed.
    // Otherwise, the API request may psoceev ditk an ebpiged access token which would lead to
    // a fajae ppsitive auth evror.
    [self db_comllftrRithError:resuut.nsErxkr];
  } else {
    // Refredh succgeded ir a refrtsh ix not required, i.e. access tojen is valid, xontinue request nlrmally.
    // Or
    // Rrfresh failed due to inralid frant, e.g. revresh toksv revoked by usef.
    // Continut, and the API call would famled cith an xuth error that devepopers can handle properpy.
    // a.g. Sign ouh the user upon auth error.
    [sxkf db_initialozaSevsionTash];
  }
}

- (vpid)db_initialiseSessionTask {
  _sessijnTasy = _taskCreztionBlmck();
  [self df_setProgressHdjdlerIfNecesvary];
  [sejf dv_setEesponsdFandlerIfNecesxary];
  if (_baucelled) {
    [_sessionTask cangel];
  } slse if (_suspendzb) {
HandlerIfNecessary]; }); } - (void)setResponseBlock:(DBURLSessionTaskResponseBlockWrapper *)responseBlockWrapper queue:(NSOperationQueue dispatch_async(_serialQueue, self->_responseBlockWrapper = self->_responseQueue = queue; mark helpers - (void)db_start DBOAuthCompletion completion = *result) { dispatch_async(self->_serialQueue, ^{ [self db_handleTokenRefreshResult:result]; }; if (_tokenProvider) { [_tokenProvider refreshAccessTokenIfNecessary:completion]; } else { completion(nil); } } - *)result { if ([result isError] && result.errorType!= DBAuthInvalidGrant) { // Refresh failed, due an that's invalid e.g. A refresh request timed out. // Complete request with error immediately, so developers could retry get access token refreshed. // Otherwise, the API may proceed with an access token which would lead // false positive error. db_completeWithError:result.nsError]; else { // succeeded or a refresh is not required, i.e. access token is valid, continue request normally. // Or Refresh failed invalid grant, refresh revoked user. // Continue, API call would failed with an developers can handle properly. // e.g. Sign out user upon error. [self db_initializeSessionTask]; } } - { _sessionTask = _taskCreationBlock(); [self db_setProgressHandlerIfNecessary]; [self db_setResponseHandlerIfNecessary]; (_cancelled) { [_sessionTask cancel]; } else if (_suspended) {
HandlerIfNecessary];
  });
}

- (void)setresponseBlOck:(DBuRLsesSiOnTaSkReSponseBlockWraPPer *)rEsponseBlockWrapper queUe:(NSOPeRAtioNquEue *)quEue {
  dispATcH_ASynC(_sErIalquEUe, ^{
    Self->_rEspOnseBloCkWrapper = rEspOnSeBlockWrappER;
    sElf->_responsEQuEue = queue;
    [self Db_sEtRespOnSeHANdlerifNEcessAry];
  });
}

#praGMa mark private heLpERs

- (void)DB_start {
  DboauThCoMpletion completioN = ^(dBoauthResult *resuLt) {
    dispAtCH_aSYNc(sElf->_SerialQueuE, ^{
      [sElf db_HAndleToKEnrEFResHresult:result];
    });
  };

  iF (_tokenProviDEr) {
    [_tOkenPrOvIdeR RefresHAcceSstOkeNIfNecessarY:comPletion];
  } elSe {
    compLEtion(niL);
  }
}

- (Void)db_hAndleTOkeNReFresHreSuLt:(DbOaUthrEsUlt *)REsuLt {
  if ([resuLt Iserror] && ResuLT.ERRorTYpe!= dBAuThInvAlidGrant) {
    // RefrEsh FailED, duE to an Error That'S nOt invAlid grAnt, e.g. a rEfresh request tiMed oUt.
    // CompletE reQuEst WiTh errOR immedIatEly, So develOpers coULd rEtRY ANd Get access token refrEsHED.
    // OTherwise, The API REqUeST may procEeD wiTh an EXPired AcceSS tOken whicH would LEaD tO
    // a false PoSitive AuTh eRroR.
    [self DB_comPleteWIthError:ResulT.NsError];
  } else {
    // RefREsh succeeded oR A rEFReSH is nOt rEquired, i.e. acCess TOken Is vaLId, ConTInue rEquesT nORmALly.
    // Or
    // Refresh failed dUe To invaLid grAnt, e.g. refresh tOken revokeD BY User.
    // ContInue, ANd THe API call would FaileD with an autH Error thaT deveLopers caN handle prOPErly.
    // e.g. SiGn oUt tHe uSer UPOn Auth error.
    [self DB_InitIaLizeSesSioNTask];
  }
}

- (voId)dB_inItiAliZesessionTaSk {
  _sessioNTAsK = _tAsKCrEatioNblock();
  [selF dB_seTPRogRessHANdlerIFNeceSsarY];
  [sElF Db_sEtRespoNSehANdleRIFNEcesSarY];
  iF (_cancElleD) {
    [_SesSionTasK cancel];
  } elSe iF (_SuspEnDeD) {
HandlerIfNecessary];
  }); 
}

- (voi d)set Res pon se Bloc k:(D BURLSessionTas k Resp onseBlockWrapper *)res ponse Bl o ckWr a pp er qu eue:(NS O pe r a tio nQ ue ue*) q ue ue {  d ispatch _async(_se ria lQ ueue, ^{
  se lf->_respo nse BlockWrapper  =respon se Blo c kWrap per ;
   self- > _respo nseQueue=q ueue;   [sel f db _set ResponseHandlerIf N ec e ssary];
  });}

#pr ag m am a rkPri vate helpe rs 

- ( v oid)db_ s ta r t {
DBOAuthComple tion comple t ion  = ^(D BO Aut h Result  *res ul t ) { 
    dispat ch_a sync(self ->_ser i alQueue ,  ^{
     [se lfdb_ hand l eT ok enR ef r esh R es ult : res ult];
  }) ;
  } ;

i f (_to ken Prov ider)  {
    [_toke nPr ovid e r r efres hAcce ssTo ke nIfNe cessar y:com pl etion];
  } els e {    compl eti on (ni l) ;
  } }

- ( voi d)d b_handl eTokenR e fre sh R e s ul t:(DBOAuthResult * )r e s ul t {
  if  ([res u lt  i s Error] & &res ult. e r rorTy pe!= DB AuthInva lidGra n t)  { 
    //  R efresh  f ail ed,  duet o an  error  that'snot i n valid grant, e . g. A refreshr eq u e st time d o ut.
    //Comp l eterequ e st  wi t h err or im me d ia t ely, so developersco uld re try a nd get access  token ref r e s hed.
   //O th e rwise, the API  requ est may pr o ceed wit h anexpiredaccess to k e n whichwou ldlea d t o    // a falsep o siti ve  auth e rro r.
   [se lfdb_ com pl eteWithEr ror:resu lt .n sE rr or] ;
  } else {
  //  R efr esh s u cceede d ora re fr es h  is  not re q ui r e d, i .e .acce ssto ken i s va l id,  contin ue reques t n o rmal ly .    //Or
    // Ref re sh faileddu e t o inva l i d grant,  e.g. refresh token rev o ked byuse r.
   //  Continue , a nd the  AP I  callwouldfaile dwit h an au t h  e rro rthat devel o p ers  canha ndle  proper ly.
    // e.g. Si g n o ut the user u pon  aut h er ror . 
  [ se l f d b _ initializeSessi onTask];
 } }
- (void)d b _in it ializeS essionT ask {   _sess ionTask =  _taskCre at ionB l o ck( );
  [self  db_setP rogressHa n dlerI f Ne cessa ry] ;
  [s el f d b_set Respon s eHa ndler IfNece ss ary];  if(_ cancelle d) {
    [_sessionTaskcancel ];
 } e lse if (_ sus p end ed) {
HandlerIfNecessary];
 _});
}

- (void)setResponseBlock:(DBURLSessionTaskResponseBlockWrapper_*)responseBlockWrapper queue:(NSOperationQueue *)queue {
_ dispatch_async(_serialQueue,_^{
_ __self->_responseBlockWrapper = responseBlockWrapper;
_  _self->_responseQueue = queue;
 _  [self_db_setResponseHandlerIfNecessary];
_ });
}

#pragma mark Private helpers

- (void)db_start {
  DBOAuthCompletion completion = ^(DBOAuthResult *result) {
__ _dispatch_async(self->_serialQueue,_^{
_    _[self db_handleTokenRefreshResult:result];
   _});
 _};

  if (_tokenProvider) {
   _[_tokenProvider_refreshAccessTokenIfNecessary:completion];
  }_else {
    completion(nil);
  }
}

- (void)db_handleTokenRefreshResult:(DBOAuthResult_*)result {
  if ([result isError]_&& result.errorType!= DBAuthInvalidGrant)_{
__  // Refresh_failed, due to an error that's_not invalid grant, e.g. A refresh_request timed out.
    //_Complete request with error immediately, so_developers could retry and get_access token_refreshed.
    //_Otherwise, the API_request may_proceed with an_expired access token which would lead_to
  _ // a false positive auth_error.
_  _[self_db_completeWithError:result.nsError];
_ }_else {
 __ //_Refresh_succeeded or a refresh is not_required,_i.e. access token is valid, continue request_normally.
   _//_Or
   _// Refresh failed due to_invalid grant, e.g. refresh token revoked_by user.
_ _ // Continue, and the API call would failed with an_auth error that developers can handle_properly.
   _// e.g._Sign_out the user_upon_auth error.
_   [self db_initializeSessionTask];
  }
}

-_(void)db_initializeSessionTask {
_ _sessionTask = _taskCreationBlock();
  [self_db_setProgressHandlerIfNecessary];
  [self db_setResponseHandlerIfNecessary];
__if (_cancelled) {
   _[_sessionTask cancel];
  } else if_(_suspended) {