ios - Facebook login through Safari not using installed App -

i have used facebook sdk facebook developer portal , completed steps written during login through facebook app default uses safari login procedure.

why doesn't use installed app purpose?

try code

-(ibaction)clk_connectwithfb:(id)sender {     fbsdkloginmanager *login = [[fbsdkloginmanager alloc] init];  // if facebook app not installed on device, falls \c fbsdkloginbehaviorbrowser. default behavior.     login.loginbehavior = fbsdkloginbehaviornative;     [login loginwithreadpermissions:@[@"email", @"user_friends",@"user_posts"] handler:^(fbsdkloginmanagerloginresult *result, nserror *error)      {          if (error)          {              // process error              nslog(@"error :%@",error);          }          else if (result.iscancelled)          {              // handle cancellations              nslog(@"error :%@",error);          }          else          {              if ([result.grantedpermissions containsobject:@"email"])              {                  [self fetchuserinfo];                  [login logout];              }          }      }]; }  -(void)fetchuserinfo {     if ([fbsdkaccesstoken currentaccesstoken])     {         [[[fbsdkgraphrequest alloc] initwithgraphpath:@"me" parameters:@{@"fields": @"id,name,link,first_name, last_name, picture.type(large), email, birthday, bio ,location ,friends ,hometown ,posts, friendlists"}]          startwithcompletionhandler:^(fbsdkgraphrequestconnection *connection, id result, nserror *error) {              if (!error)              {                  nslog(@"result :%@",result);                  nslog(@"friend :%@",[[result valueforkey:@"friends"]objectforkey:@"data"]);                  nsstring *photostring=[[[result valueforkey:@"picture"] objectforkey:@"data"] valueforkey:@"url"];                  photostring = [photostring stringbyreplacingoccurrencesofstring:@"&" withstring:@"%26"];                  // [self userlogin:[result valueforkey:@"email"] username:[result valueforkey:@"name"] photourl:photostring logintype:@"fb" phoneno:@""];              }          }];               } } 

i hope great.

if answer accept , upvote answer