When to release a NSString in iPhone

Question

up vote 7 down vote favorite

7

I have the following method

   -(NSMutableArray *) getPaises {
     NSMutableArray * paises;
     paises = [[NSMutableArray alloc] init];
     while( get new row ) {
      NSString *aPais =  [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 0)];
      [paises addObject:aPais];
     }
     return paises;
    }

I am not releasing the aPais, because if I do it the application crashes. I don't know when or if whether I should release it somewhere after using it and, if so, how do I do it. Just release the NSMutableArray is enough? Or do I have to traverse it and release each object?

And if I don't have to release it, who is the responsible for releasing?

edited Mar 2 '09 at 12:53

andynormancx
3,271 10 26

asked Mar 2 '09 at 12:38

Sacha Fuentes
45 1 4

A note regarding method naming: In Cocoa, a method named “getFoo” returns foo by reference: - (void) getFoo:(out NSMutableArray **)outArray. To be consistent with Cocoa naming conventions, you should name your method simply “paises”. – Peter Hosey Mar 2 '09 at 18:13

feedback

A note regarding method naming: In Cocoa, a method named “getFoo” returns foo by reference: - (void) getFoo:(out NSMutableArray **)outArray. To be consistent with Cocoa naming conventions, you should name your method simply “paises”.

squelart · Answer 1 · 2009-03-02 13:14:48Z

As epatel said, you don't need to release that particular string. If you wanted to be more proactive, you could do this instead:

-(NSMutableArray *) getPaises {
    NSMutableArray * paises;
    paises = [[[NSMutableArray alloc] init] autorelease];
    while( get new row ) {
        NSString *aPais =  [[NSString alloc] initWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 0)];
        [paises addObject:aPais];
        [aPais release];
    }
    return paises;
}

In summary:

[[NSString alloc] initWith...] -> You must release or autorelease.
[NSString stringWith...] -> No need to release.

-- Edit: Added autorelease for paises, as you are returning it. When you return an object, always autorelease it if you have alloc&init'd it.

Thanks a lot. I'm releasing the NSMutableArray manually, but the autorelease is a better option. Gonna change it.

NSString的一点tips

When to release a NSString in iPhone

2 Answers

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