How can I reference an Object and edit it's properties from a NSMutableArray?

Question

NSMutableArray *persons = [ [ NSMutableArray alloc ] init ];

How can I edit person attributes without doing something like:

Person *p = [ [ Person alloc ] init ];
p = [ persons objectAtIndex:0 ];
p.name = "James Foo";
[ persons replaceObjectAtIndex: ([ persons count ] - 1 )  withObject:p];

I would like to do something like:

[ persons objectAtIndex:0 ].name = "James Foo";

It should be @"James Foo". You need the @ sign in there. — Dave DeLong
– Dave DeLong, Commented Jan 14, 2010 at 20:28

Seva Alekseyev · Accepted Answer · 2010-01-14 20:24:33Z

6

But you can. You have to cast the generic id into your type though:

((Person*)[persons objectAtIndex:0]).name = "James Foo";

answered Jan 14, 2010 at 20:24

Seva Alekseyev

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1 Comment

Chuck Over a year ago

Or use the setter directly. [[persons objectAtIndex:0] setName:@"Foo"]

Kevlar · Accepted Answer · 2010-01-14 23:34:00Z

2

This example code also has a memory leak; you shouldn't need to alloc a new person instance in that case; you could just do the following if you don't want to cast anything:

Person *p = [persons objectAtIndex:0];
p.name = @"James Foo";

and you don't need to re-add it to the array since getting the object at a location doesn't remove it from the array on its own.

answered Jan 14, 2010 at 23:34

Kevlar

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2 Comments

Mc- Over a year ago

Thanks, I'm newbie on iPhone and Objective C and i'm trying to follow best practices!

Seva Alekseyev Over a year ago

Best practices are for those who understand the rationale behind them. Try to get something out of the door first, then read up on best practices. Premature optimization, blah blah.

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