Class Factory Method with Multiple Parameters - objective-c

Question

I am practicing my Objective C skills and have come across a small issue, although I can't seem to find a straight answer to this issue anywhere I look. In the Apple developer guides I am reading, there is nothing in there telling me how to use a class factory method with multiple parameters (say 3 parameters) and return the initialized object via the overridden init method.
Here I have a simple class called XYZPerson.
#implementation XYZPerson
// Class Factory Method
+ (id)person:(NSString *)firstName with:(NSString *)lastName andWith:(NSDate *)dateOfBirth {
// need to return [ [self alloc] init with the 3 paramaters]; here
// Or some other way to do so..
}
// Overridden init method
- (id)init:(NSString *)firstName with:(NSString *)lastName andWIth:(NSDate *)dateOfBirth {
self = [super init];
if (self) {
_firstName = firstName;
_lastName = lastName;
_dateOfBirth = dateOfBirth;
}
return self;
}
// Use the initialized instance variables in a greeting
- (void)sayHello {
NSLog(#"Hello %# %#", self.firstName, self.lastName);
}
And then in my main I am instantiating an XYZPerson object
XYZPerson *person = [XYZPerson person:#"John" with:#"Doe" andWith:[NSDate date]];
[person sayHello];
Can anybody give me a small pointer on how to do this correctly?

Answer 1

If I understand your question, you want the following:
+ (id)person:(NSString *)firstName with:(NSString *)lastName andWith:(NSDate *)dateOfBirth {
XYZPerson *result = [[self alloc] init:firstName with:lastName andWith:dateOfBirth];
return result;
}
If you aren't using ARC, add an autorelease to the return.
BTW - change the return type of the init method to instancetype instead of id.

Answer 2

#implementation XYZPerson
// Class Factory Method
+ (instanceType ) person:(NSString *)firstName with:(NSString *)lastName andWith:(NSDate *)dateOfBirth {
return [[[self class] alloc]init: firstName with: lastName andWith:dateOfBirth];
}
- (instanceType ) init:(NSString *)firstName with:(NSString *)lastName andWIth:(NSDate *)dateOfBirth {
self = [super init];
if (self) {
_firstName = [firstName copy];
_lastName = [lastName copy];
_dateOfBirth = [dateOfBirth copy];
//nb added copy to each of these, we do not own these objects, they could be lost to us..
/// or you could do this instead..
//assuming you synthesised getters/setters for (strong) properties..
[self setFirstName:firstName];
[self setLastName:lastName];
[self setDateOfBirth: dateOfBirth];
}
return self;
}