What is the difference between
NSMutableArray* p = [[NSMutableArray alloc] initWithObjects:...]
and
NSMutableArray* p = [NSMutableArray arrayWithObjects:...]
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4 Answers
In the first one, you have the ownership of array object & you have to release them.
NSMutableArray* p = [[NSMutableArray alloc] initWithObjects:...];
[p release];
& last one you dont need to release as you don't have the ownership of array object.
NSMutableArray* p = [NSMutableArray arrayWithObjects:...]; //this is autoreleased
If you call release in this, then it will crash your application.
2 Comments
glenn sayers
Isn't arrayWithObjects autoreleased by default?
Meenakshi
yes this is autorelease...we don't need to call autorelease. Thanks for editing fzwo :)
[NSMutableArray arrayWithObjects:] is the same as [[[NSMutableArray alloc] initWithObjects:] autorelease]
3 Comments
Rocky
so, which is the better way? To alloc and release manually or to alloc with "autorelease"?
fzwo
@ZhaoRocky In practice, the best way is to use ARC. If you can't use ARC, read up on manual reference counting. Neither manual retain/release nor autorelease are inherently better, it depends entirely on the situation.
Catfish_Man
Indeed. If one way was just "better" in all situations, the other one wouldn't exist.
In practice, there is no difference if you're on ARC.
The latter basically is just a shorthand for [[NSMutableArray alloc] initWithObjects: ...], except the returned array is autoreleased (which is important if you're still doing manual reference counting).
2 Comments
Catfish_Man
Not quite. The latter autoreleases the return value.
fzwo
Right. In practice, on ARC, there is no difference. Thanks for pointing that out, though. I'll edit my answer.
What I think the difference is that: initWithObjects is a instance method, and arrayWithObject is a class method.
1 Comment
fzwo
While that is certainly true, it's also completely irrelevant :)