create to dimensional array of integer in objective c

Question

I want to implement thing like that but i get error in add because of id !!!

NSMutableArray *rgbarray = [[NSMutableArray alloc] init];
 NSInteger rgb[3];
            const CGFloat *components = CGColorGetComponents(cgcolor);
            CGFloat cgred = components[0];
            CGFloat cggreen = components[1];
            CGFloat cgblue = components[2];
            rgb[0] = cgred;
            rgb[1] = cggreen;
            rgb[2] = cgblue;

            [rgbarray addObject:rgb];

i want to add rgb instead of id ?

possible duplicate of 2D Array Declaration - Objective C

Richard J. Ross III
– Richard J. Ross III

2012-05-09 06:11:15 +00:00
Commented May 9, 2012 at 6:11 — Richard J. Ross III
– Richard J. Ross III, Commented May 9, 2012 at 6:11

Jesse Black · Accepted Answer · 2012-05-09 06:39:51Z

3

You can only add pointers to instances of objects into NSMutableArray

You can use a NSDictionary or create your own subclass of NSObject to wrap the 3 values.

NSDictionary * rgbDictionary = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithFloat:cgred], @"cgred", [NSNumber numberWithFloat:cggreen], @"cggreen", [NSNumber numberWithFloat:cgblue], @"cgblue", nil];

[rgbarray addObject:rgbDictionary];

To retrieve the values

NSDictionary * rgbDictionary = [rgbArray objectAtIndex:0];
CGFloat cgred = [[rgbDictionary objectForKey:@"cgred"] floatValue];
CGFloat cggreen = [[rgbDictionary objectForKey:@"cggreen"] floatValue];
CGFloat cgblue = [[rgbDictionary objectForKey:@"cgblue"] floatValue];

I would actually use the subclass approach. Since you were trying to code with a C array for your values, the NSDictionary approach will get you past the error.

edited May 9, 2012 at 6:39

answered May 9, 2012 at 6:07

Jesse Black

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5 Comments

Richard J. Ross III Over a year ago

You really should just be using a C-array here, as NSArray w/ NSNumbers are incredibly slow compared to a c array.

kartal Over a year ago

I got this error when i tried to retrieve them back Initializing 'CGFloat' (aka 'float') with an expression of incompatible type 'id';

Jesse Black Over a year ago

@salamonti I had typed the code into the browser only. I forgot to access the floatValue. Since we populated the NSDictionary with NSNumbers, you need to use the floatValue property to access the primitive float from the NSNumber

kartal Over a year ago

Is it require any import file ?

Jesse Black Over a year ago

@salamonti the adjusted code doesn't require an import. Using the method floatValue as a opposed to the property. It is easier to get it to compile

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