objective c - NSTimeinterval problem for date in iphone sdk -

i converting date nstimeinterval code below:

nsdate *currentdate = [nsdate date]; nstimeinterval currentyinterval = [appdelegate settimeinterval:currentdate];     nsdate *expirydate = [appdelegate setreversedate:warrobj.expiredon];   nstimeinterval expiryinterval = [appdelegate settimeinterval:expirydate]; //here getting nil value , exception generated. //it happens in 3.1   -(nstimeinterval )settimeinterval:(nsdate *)selecteddate {     nsdateformatter *dateformatter = [[nsdateformatter alloc]init] ;     [dateformatter setdateformat:@"dd-mmm-yyyy 00:00:00"];     nsstring *currstr = [dateformatter stringfromdate:selecteddate];     nsdate *newcurrentdate = [dateformatter datefromstring:currstr];      nstimeinterval timeinterval = [newcurrentdate timeintervalsincereferencedate];     [dateformatter release];     return timeinterval; } 

can suggest me how rid of this.

thanks all, madan.

nstimeinterval typedef double, not object:

getting time interval:

nstimerinterval timeinterval = [[nsdate date] timeintervalsincereferencedate];   nsdate *expirydate = [appdelegate setreversedate:warrobj.expiredon]; nstimeinterval expiryinterval = [expirydate timeintervalsincereferencedate]; 

creating date time interval:

nstimeinterval onehour = 60*60; nsdate *date = [nsdate datewithtimeintervalsincereferencedate:timeinterval - onehour];