iphone - memory management and class member variable -

i have following code:

  @interface reservation : rkobject {     nsnumber * _uid;     nsnumber * _did;     nsnumber * _rid;     nsstring* _origin;     nsstring* _destination;     nsstring* _time_range;     nsdate * _start_date;     nsdate * _end_date; }  @property (nonatomic, retain) nsdate * start_date; @property (nonatomic, retain) nsdate * end_date; @property (nonatomic, retain) nsnumber * uid; @property (nonatomic, retain) nsnumber * did; @property (nonatomic, retain) nsnumber * rid; @property (nonatomic, retain) nsstring * time_range; @property (nonatomic, retain) nsstring * origin; @property (nonatomic, retain) nsstring * destination; @end  #import "reservation.h"  @implementation reservation @synthesize time_range= _time_range; @synthesize origin=_origin; @synthesize destination=_destination; @synthesize uid=_uid; @synthesize did=_did; @synthesize rid=_rid; @synthesize start_date=_start_date; @synthesize end_date=_end_date;   + (nsdictionary*) elementtopropertymappings {     return [nsdictionary dictionarywithkeysandobjects:             @"time_range", @"time_range",             @"origin_address", @"origin",             @"destination_address", @"destination",             @"uid", @"uid",             @"did", @"did",             @"rid", @"rid",             @"start_datetime", @"start_date",             @"end_datetime", @"end_date",             nil];  }   /* + (nsdictionary*)elementtorelationshipmappings {     return [nsdictionary dictionarywithkeysandobjects:             @"nsdate", @"start_date",             @"nsdate", @"end_date",             nil]; }  */  - (void)dealloc {     [_start_date release];     [_end_date release];     [_uid release];     [_did release];     [_rid release];     [_origin release];     [_destination release];     [_time_range release];     //[_deal release];     //[_route release];     [super dealloc]; } 

@end

@interface reservationviewcontroller : uiviewcontroller <uitableviewdelegate, uitableviewdatasource, rkobjectloaderdelegate>{     reservation * myres; }  @property (nonatomic, retain) reservation * myres;  #import "reservationviewcontroller.h"   @implementation reservationviewcontroller @synthesize myres;  - (ibaction)makereservation:(id)sender {     self.myres = [[[reservation alloc] init] autorelease];       myres.start_date = [df datefromstring:[nsstring stringwithformat:@"%@ %@", [self.data objectforkey:@"date"], [self.data objectforkey:@"start_time"]]];     myres.end_date = [df datefromstring:[nsstring stringwithformat:@"%@ %@", [self.data objectforkey:@"date"], [self.data objectforkey:@"end_time"]]];     nslog(@"date %@", myres.start_date); }  - (void)objectloader: (rkobjectloader*) objectloader didloadobjects:(nsarray *)objects {         interval * res_int = [[interval alloc] init];         res_int.date1 = myres.start_date; //why null here         res_int.date2 = myres.end_date; //why null here         res_int.rid =  [[objects objectatindex:0] rid];         [[locationdictionary sharedlocationdictionary] addlocationtodictionary:[self.data objectforkey:@"route"] withkey:res_int]; 

}

the question why res_int.date1 null when tried printing out? when print myres.start_date inside method makereservation, prints appropriately can explain me , how fix it?

update:

i have done following @ setter:

-(void) setstart_date:(nsdate *) boo {      nsassert(boo != nil, @"why nil");     _start_date = boo;      } 

at end stack trace got is:

 *** terminating app due uncaught exception 'nsinternalinconsistencyexception', reason: 'why nil' *** call stack @ first throw: (     0   corefoundation                      0x019ac5a9 __exceptionpreprocess + 185     1   libobjc.a.dylib                     0x01b00313 objc_exception_throw + 44     2   corefoundation                      0x01964ef8 +[nsexception raise:format:arguments:] + 136     3   foundation                          0x014013bb -[nsassertionhandler handlefailureinmethod:object:file:linenumber:description:] + 116     4   project                            0x00012d42 -[reservation setstart_date:] + 194     5   foundation                          0x0137e5e5 -[nsobject(nskeyvaluecoding) setvalue:forkey:] + 285     6   project                           0x0004c7b3 -[rkobjectmapper updatemodel:ifnewpropertyvalue:forpropertynamed:] + 172     7   project                            0x0004cd55 -[rkobjectmapper setpropertiesofmodel:fromelements:] + 754     8   project                            0x0004d8f3 -[rkobjectmapper updatemodel:fromelements:] + 50     9   project                            0x0004bb7a -[rkobjectmapper mapobject:fromdictionary:] + 201     10  project                            0x0004ba42 -[rkobjectmapper mapobject:fromstring:] + 148     11  project                            0x0004927b -[rkobjectloader processloadmodelsinbackground:] + 537     12  foundation                          0x01370cf4 -[nsthread main] + 81     13  foundation                          0x01370c80 __nsthread__main__ + 1387     14  libsystem.b.dylib                   0x931a085d _pthread_start + 345     15  libsystem.b.dylib                   0x931a06e2 thread_start + 34 ) terminate called after throwing instance of 'nsexception' 

what calling sequence of makereservation (from ibaction) , objectloader? possible objectloader called before makereservation myres hasn't been initialized yet?

what interface definition did property of reservation? line:

myres.did = [[nsnumber alloc] initwithint:[[[data objectforkey:@"discount"] did] intvalue]]; 

if defined (nonatomic, retain) may retaining nsnumber object without releasing it. if so, change line to:

myres.did = [nsnumber numberwithint:[[[data objectforkey:@"discount"] did] intvalue]]; 

you should uncomment line:

//[res_int release]