Which way to initialize NSString* pointer in class

Question

I'm using NSString in my classes and often need to copy string value to another class. But my question is how should I initialize string in, for example init? (value is class member and the following calls are in init)

value = [NSString stringWithCString:inStrning encoding:NSASCIIStringEncoding];

or

value = [[NSString alloc] initWithCString:inStrning encoding:NSASCIIStringEncoding];

What is the difference here? Does a memory allocated in 1st call released when init finishes? I'm using value as a assign property. Would it be better to use copy?

And what about copying string when I'm passing it to class using some method? Example:

-(id) initWithObjectTypeStr:(NSString*)inTypeStr
{
    ...
    objectTypeStr = [NSString stringWithString:inType];
    //or 
    objectTypeStr = [[NSString alloc] initWithString:inType];
}

objectTypeStr is not defined as property so it has default properties (assign I think).

What is the best practice to use in this case?

see my blog post on memory management for this - makebetterthings.com/blogs/iphone/… — Saurabh
– Saurabh, Commented Apr 7, 2011 at 11:32

rckoenes · Accepted Answer · 2019-04-29 07:52:12Z

2

[NSString alloc] initWithString:@""]

Gives back a string you own, you will have to release it.

[NSString stringWithString:@""]

Returns an autorelease object that will release and cleaned up by the autoreleasepool.

I would suggest you read the memory management documentation.

edited Apr 29, 2019 at 7:52

answered Apr 7, 2011 at 11:30

rckoenes

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2 Comments

dobry Over a year ago

Thanks, that cleared a lot. Apple guides are more readable when I read them with focus on my problem.

Muschel Over a year ago

The link is unfortunately dead now.

visakh7 · Accepted Answer · 2011-04-07 11:31:07Z

1

The difference is that in this case objectTypeStr = [NSString stringWithString:inType]; objectTypeStr is auto-released and you dont own the object.

Whereas in objectTypeStr = [[NSString alloc] initWithString:inType]; you take ownership of the object since you are allocating it using alloc or new so its your responsibility to release it after its use

answered Apr 7, 2011 at 11:31

visakh7

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