ios - nil object in NSDictionary -

i have nsdictionary read values in 2 different methods in code, in 1 of methods value of key retrieved correctly whereas in other method nil.

this method works:

-(void)drawdriver:(nsstring*)driverid withposition:(cllocationcoordinate2d)position withrotation:(float)bearing isavailable:(bool)isdriveravailable{      gmsmarker *drivermarker = [driverslist objectforkey:driverid];     if (drivermarker != nil) {         // work     } } 

and it's called other method:

- (void) socketio:(socketio *)socket didreceivemessage:(socketiopacket *)packet {     nsmutabledictionary *datos = (nsmutabledictionary*)packet.data;     nsdictionary *driverid = datos[@"from"];     nsstring *id = [driverid objectforkey:@"id"];      //gets other values      nslog(@"socket message: driverid: %@, position %f,%f, isavailable:%d", id, latitude, longitude, isdriveravailable);      //call first method     [self drawdriver:id withposition:position withrotation:bearing isavailable:isdriveravailable];  } 

and method doesn't work (returns nil drivermarker):

-(void)updatemapfortripwithdriver:(nsstring *)driverid {      gmsmarker *drivermarker = [driverslist objectforkey:driverid];     if (drivermarker != nil) {         //do work     } } 

and called here:

- (void)updatetripwithdata:(nsdictionary *)data {      //this nsdictionary comes notification     nsstring *newstatus = [[data objectforkey:@"aps"] objectforkey:@"alert"];      if ([newstatus isequaltostring:no_trip]) {      } else if ([newstatus isequaltostring:waiting_confirmation]) {      } else if ([newstatus isequaltostring:driver_on_the_way]) {          //get driverid , call other method         nsstring *driverid = [data objectforkey:@"driver_id"];         [self updatemapfortripwithdriver:driverid];     } } 

as can see both methods have exact same code retrieve object still different results. difference find when put breakpoints on methods , found:

on first method, although pass driverid nsstring, somehow it's read nsfcnumber , seems work because value no problems.

but on second method key read actual nsstring reason makes method return nil object exists on nsdictionary.

how can second method work , return right value?