Dedicated Initializer in Objective-C -

i newbie objective-c. have 'xyzperson' class attributes {firstname, lastname, dateofbirth} , want when write "xyzperson *person=[[xyzperson alloc] init]" in main, should call overridden 'init' method should in-turn call designated initializer , initializes object defined values.

my code snippets. http://pastebin.com/ffxnddhf

#import <foundation/foundation.h> #import "xyzshoutingperson.h"  int main(int argc, const char * argv[]) {     @autoreleasepool {         xyzperson *person=[[xyzperson alloc] init];         if(person) {             [person sayhello];         }         else {             nslog(@"person object null");         }     }     return 0; }  -(id)init {     self=[super init];     return [self initwithfirstname:@"ankit" lastname:@"sehra" dob:01/01/2000]; }  -(id)initwithfirstname:(nsstring *)afirstname lastname:(nsstring *)alastname dob:(nsdate *)adateofbirth {     _firstname=afirstname;     _lastname=alastname;     _dateofbirth=adateofbirth; }      -(void)sayhello; {     nslog(@"%@ %@ %@",self.firstname,self.lastname,self.dateofbirth); } 

write output of program "person object null", want print firstname, lastname , dob.

if class has several init methods, 1 of them "designated initializer". 1 calls [super initxxx]. in example, initwithfirstname:lastname:dob: designated initializer , should this:

-(id)initwithfirstname:(nsstring *)afirstname lastname:(nsstring *)alastname dob:(nsstring *)adateofbirth {     self = [super init];     if (self) {         _firstname=afirstname;         _lastname=alastname;         _dateofbirth=adateofbirth;     }     return self; } 

(i have changed type of dateofbirth property , dob argument nsstring , explain later.)

all other init methods call designated initializer (and not [super initxxx]), in example init:

-(id)init {     return [self initwithfirstname:@"ankit" lastname:@"sehra" dob:@"01/01/2000"]; } 

note (among several other errors), "01/01/2000" not nsdate,

return [self initwithfirstname:@"ankit" lastname:@"sehra" dob:01/01/2000]; 

does not make sense. therefore, first working example you, have changed argument type nsstring.