NSMutableArray and NSArray initialization

Question

Is there a better way to initialize a 2 dimensional array in objective-c than this:

NSNumber *a = [[NSNumber alloc] initWithInt:0];
NSNumber *b = [[NSNumber alloc] initWithInt:1];
NSMutableArray *template = [[NSMutableArray alloc] initWithCapacity:16];
switch (myInt) {
    case 0:
        [template addObject:[[NSArray alloc] initWithObjects:b, b, b, b, b, b, b, b, nil]];
        [template addObject:[[NSArray alloc] initWithObjects:b, b, b, b, b, b, b, b, nil]];
        [template addObject:[[NSArray alloc] initWithObjects:b, a, b, b, b, b, b, b, nil]];
        [template addObject:[[NSArray alloc] initWithObjects:b, b, a, b, b, b, b, b, nil]];
        [template addObject:[[NSArray alloc] initWithObjects:b, b, b, a, b, b, b, b, nil]];
        [template addObject:[[NSArray alloc] initWithObjects:b, b, b, b, a, b, b, b, nil]];
        [template addObject:[[NSArray alloc] initWithObjects:b, b, b, b, b, b, b, b, nil]];
        [template addObject:[[NSArray alloc] initWithObjects:b, b, b, b, b, b, b, b, nil]];
        [template addObject:[[NSArray alloc] initWithObjects:b, b, b, b, b, b, b, b, nil]];
        [template addObject:[[NSArray alloc] initWithObjects:b, b, b, b, b, b, b, b, nil]];
        [template addObject:[[NSArray alloc] initWithObjects:b, b, b, b, b, b, b, b, nil]];
        [template addObject:[[NSArray alloc] initWithObjects:b, b, b, b, b, b, b, b, nil]];
        [template addObject:[[NSArray alloc] initWithObjects:b, b, b, b, b, b, b, b, nil]];
        [template addObject:[[NSArray alloc] initWithObjects:b, b, b, b, b, b, b, b, nil]];
        [template addObject:[[NSArray alloc] initWithObjects:b, b, b, b, b, b, b, b, nil]];
        [template addObject:[[NSArray alloc] initWithObjects:b, b, b, b, b, b, b, b, nil]];
        break;
/* more */
}

If you change later the value of "a" or "b", will it also change in all the arrays added to template? — The dude, Feb 08 '12 at 08:36
@iOS developer NSNumber is immutable object which value cannot be changed — Bryan Chen, Feb 08 '12 at 10:09
different options http://stackoverflow.com/questions/638129/how-to-declare-a-two-dimensional-array-of-string-type-in-objective-c — Girish Kolari, Feb 08 '12 at 10:20
@xlc0212 thank you so much! But in case array was populated with mutable objects, it would change in all the arrays added to template, right? — The dude, Feb 08 '12 at 16:33

score 0 · Answer 1 · answered Feb 08 '12 at 08:18

0

I cann't find regularity in your arrays. At least you can wrap some code into cycle

id obj = [[NSArray alloc] initWithObjects:b, b, b, b, b, b, b, b, nil];

for (int i = 0; i<9; ++i){
    [template addObject: obj];
}

answered Feb 08 '12 at 08:18

beryllium

29,669
15
106
125

score 0 · Answer 2 · answered Feb 08 '12 at 10:07

assume you want to make a 2d array of NSNumber

const int templateContent[][8] = { // put your data to this array
    1, 1, 1, 1, 1, 1, 1, 1,
    1, 0, 1, 1, 1, 1, 1, 1,
    // more...
};
const int dim = sizeof(templateContent)/sizeof(int[8]);
NSNumber *numbers[2]; // assume your only need two numbers
for (int i = 0; i < sizeof(numbers)/sizeof(id); i++) {
    numbers[i] = [NSNumber numberWithInt:i];
}
NSMutableArray *template = [[NSMutableArray alloc] initWithCapacity:16];
for (int i = 0; i < dim; i++) {
    [template addObject:[NSArray arrayWithObjects:
                         numbers[templateContent[i][0]], 
                         numbers[templateContent[i][1]], 
                         numbers[templateContent[i][2]], 
                         numbers[templateContent[i][3]], 
                         numbers[templateContent[i][4]], 
                         numbers[templateContent[i][5]], 
                         numbers[templateContent[i][6]], 
                         numbers[templateContent[i][7]], nil]];
}

score 0 · Answer 3 · answered Feb 08 '12 at 10:07

0

Use nsdictionary to hold numbers and then store the dictionary in nsarray

answered Feb 08 '12 at 10:07

Piyush Kashyap

1,965
1
14
16

NSMutableArray and NSArray initialization

3 Answers3