Question

Firstly, I wrote my customized setter for an NSString* like this:

- (void)setDateString:(NSString *)newDateString {
    self.dateString = newDateString;
    NSInteger dateNumber = [dateString integerValue];
        // this line causes crash

    // do something here..blah blah
}

then the program stops due to infinitely many threads which does [XXX setDateString:].

After several useless tries I found this question/answer which tells me

do not use self. inside of custom accessors. access the variable directly,

so I made my code into

- (void)setDateString:(NSString *)newDateString {
    //self.dateString = newDateString;
    dateString = newDateString;
    NSInteger dateNumber = [dateString integerValue];

    // do something here..blah blah
}

then everything works like a charm!!

---

I am a junior developer of some objective languages, and a newbie to Objective-C.

I want to learn in details for this issue, instead of solving problems without understanding the reason.

So please provide me with some materials/website to understand more about this.

BTW, I use ARC.

Thank you all. 🙂

Answer 1

self.dateString = newDateString;

is equivalent to

[self setDateString:newDateString];

so this will cause infinite recursion because you are calling it inside -setDateString:.

See also Difference between self.ivar and ivar?.