arrayByAddingObjectsFromArray?

Question

I am not sure what I am doing wrong here? I have tried various combinations to try and copy an array into variable mmm. I am trying to learn how to create a 2D array and then run a loop to place init_array into 10 columns.

// NSMutableArray *mmm = [NSMutableArray arrayWithCapacity: 20];
NSMutableArray *kkk = [NSMutableArray arrayWithObjects: @"a", @"b", @"cat", @"dog", nil];
NSMutableArray *mmm; //= [NSMutableArray arrayWithObjects: @"1", @"2", @"3", @"4", nil];

[mmm arrayByAddingObjectsFromArray:kkk];

NSLog(@"Working: %@",[mmm objectAtIndex:3]);

thanks...

so this works from the given answer:

NSMutableArray *mmm = [NSMutableArray arrayWithCapacity: 20];
NSMutableArray *kkk = [NSMutableArray arrayWithObjects: @"a", @"b", @"cat", @"dog", nil];

[mmm addObjectsFromArray:kkk];

NSLog(@"Working: %@",[mmm objectAtIndex:3]);

Wevah · Accepted Answer · 2011-07-15 03:41:20Z

24

arrayByAddingObjectsFromArray: returns a new (autoreleased) NSArray object. What you want is addObjectsFromArray:.

answered Jul 15, 2011 at 3:41

Wevah

28.2k7 gold badges86 silver badges74 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Kristen Martinson Over a year ago

do I have to "retain" this to use outside of the scope?

Chuck Over a year ago

@Kristen Martinson: Object lifetimes aren't really related to scope. You have to retain to keep an object you don't own alive past the draining of the current autorelease pool.

Chuck · Accepted Answer · 2011-07-15 03:44:53Z

10

arrayByAddingObjectsFromArray: returns a new NSArray that includes the objects in the receiver followed by the objects in the argument. The code you posted there, with mmm unset, will probably just crash since mmm doesn't point to an NSArray object. If you had assigned an array to mmm, then it would return (@"1", @"2", @"3", @"4", @"a", @"b", @"cat", @"dog") — but you don't assign the result to any variable, so it just goes nowhere. You'd have to do something like NSArray *yetAnotherArray = [mmm arrayByAddingObjectsFromArray:kkk].

If you have an NSMutableArray and you want to add objects from another array, use addObjectsFromArray:.

answered Jul 15, 2011 at 3:44

Chuck

238k31 gold badges306 silver badges392 bronze badges

1 Comment

Kristen Martinson Over a year ago

Since the other guy was first with the solution, I had to chose him... but you added more info so i gave you a point

Collectives™ on Stack Overflow

arrayByAddingObjectsFromArray?

2 Answers 2

2 Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related