NSMutableArray arrayWithArray: vs. initWithArray:

Question

These both work in my app without any noticeable difference:

1)

theArray = [[NSMutableArray alloc] initWithArray:[NSKeyedUnarchiver unarchiveObjectWithData:theData]];

2)

theArray = [NSMutableArray arrayWithArray:[NSKeyedUnarchiver unarchiveObjectWithData:theData]];
[theArray retain];

However, are they really equivalent? (1) has an alloc statement, whereas (2) does not. Is one preferable over the other?

Community · Accepted Answer · 2017-05-23 11:55:22Z

5

The effect is the same. But (2) is less efficient (a convenient method = alloc + init + autorelease).

alloc → init
alloc → init → autorelease → retain

The preferred way is not to copy the array.

theArray = [[NSKeyedUnarchiver unarchiveObjectWithData:theData] retain];

BTW, I notice that you have been asking a lot of basic questions about iPhone OS development. Please go through the tutorials on these first.

edited May 23, 2017 at 11:55

CommunityBot

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answered Sep 20, 2010 at 8:26

kennytm

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2 Comments

Greg M. Krsak Over a year ago

Kenny, wouldn't it be cool if StackOverflow was the best resource on the web, even for "beginner" questions? In many ways, it is; however, redirecting those types of questions to your favorite tutorials isn't in-keeping with that vision. It's up to you.

badweasel Over a year ago

Agreed. I'm a seasoned coder with decent apps under my belt and I still come here with questions like this. My least favorite answer to find here is "we're not here to teach to you program".. really? Cause then why are you here? Cause I'm here to learn and to help people learn. And often times I can get a quick answer to something much faster here than waiting through a 30 - 60 minute tutorial that starts with making a ios project.

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