Objective-C accessing / changing array elements in a multidimensional array (NSArray)

Question

I'm trying to change a value in a multidimensional array but getting a compiler error:

warning: passing argument 2 of 'setValue:forKey:' makes pointer from integer without a cast

This is my content array:

NSArray *tableContent = [[NSArray alloc] initWithObjects:
                [[NSArray alloc] initWithObjects:@"a",@"b",@"c",nil],
                [[NSArray alloc] initWithObjects:@"d",@"e",@"f",nil],
                [[NSArray alloc] initWithObjects:@"g",@"h",@"i",nil],
                 nil];

This is how I'm trying to change the value:

[[tableContent objectAtIndex:0] setValue:@"new value" forKey:1];

Solution:

 [[tableContent objectAtIndex:0] setValue:@"new val" forKey:@"1"];

So the array key is a string type - kinda strange but good to know.

dreamlax · Accepted Answer · 2010-01-18 20:15:32Z

11

NSMutableArray *tableContent = [[NSMutableArray alloc] initWithObjects:
                    [NSMutableArray arrayWithObjects:@"a",@"b",@"c",nil],
                    [NSMutableArray arrayWithObjects:@"d",@"e",@"f",nil],
                    [NSMutableArray arrayWithObjects:@"g",@"h",@"i",nil],
                     nil];

[[tableContent objectAtIndex:0] replaceObjectAtIndex:1 withObject:@"new object"];

You don't want to alloc+init for the sub-arrays because the retain count of the sub-arrays will be too high (+1 for the alloc, then +1 again as it is inserted into the outer array).

answered Jan 18, 2010 at 20:15

dreamlax

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Comments

NSResponder · Accepted Answer · 2010-01-18 19:35:51Z

2

You're creating immutable arrays, and trying to change the values stored in them. Use NSMutableArray instead.

answered Jan 18, 2010 at 19:35

NSResponder

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Chuck · Accepted Answer · 2010-01-18 21:51:10Z

1

You want either NSMutableArray's insertObject:atIndex: or replaceObjectAtIndex:withObject: (the former will push the existing element back if one already exists, while the latter will replace it but doesn't work for indices that aren't already occupied). The message setValue:forKey: takes a value type for its first argument and an NSString for its second. You're passing an integer rather than an NSString, which is never valid.

edited Jan 18, 2010 at 21:51

answered Jan 18, 2010 at 19:54

Chuck

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3 Comments

dan Over a year ago

There is no message like setObject:atIndex: but setObject:forKey:. But still get the same error.

dreamlax Over a year ago

There is no setObject:atIndex: for NSMutableArray, instead there is replaceObjectAtIndex:withObject:. developer.apple.com/mac/library/documentation/Cocoa/Reference/…

Chuck Over a year ago

Apologies, posted while running out the door and made up a method. I've corrected to explain the two methods that I was conflating in my head.

Alfian Busyro · Accepted Answer · 2012-02-28 09:30:50Z

0

Sorry for responding 1 and half years old question :D
I got the same problem, and at last I solved it with counting the elements, then do addObject to push to the array element

answered Feb 28, 2012 at 9:30

Alfian Busyro

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