NSArray initialization with numbers

Question

I was wondering how do I go about creating an NSArray with say numbers 1-100 to be used in a UIPickerView.

I know from other programming classes I could do:

int array[100];
for (int i=1, i<=100, i++)
   array[i]=i;

But I am not sure how to something equivalent with NSArray, instead of manually typing in all the values. I searched it online and I saw someone did it with calloc and was unsure if that was the best method, or if I could wrap the int into a NSNumber somehow and have each NSNumber go into my array. And if I was to do this procedure, would I then create a NSMutableArray and addObject each time running through the loop? I want these values loaded whenever the user goes to the screen.

Just indent your code with atleast 4 spaces and it will become a code block. — Juha Syrjälä
– Juha Syrjälä, Commented Dec 1, 2009 at 19:40

Skirwan · Accepted Answer · 2009-12-01 19:50:36Z

6

Either:

NSArray * array = [NSArray array];
for ( int i = 1 ; i <= 100 ; i ++ )
    array = [array arrayByAddingObject:[NSNumber numberWithInt:i]];

[array retain];

Or:

NSMutableArray * array = [[NSMutableArray alloc] initWithCapacity:100];
for ( int i = 1 ; i <= 100 ; i ++ )
    [array addObject:[NSNumber numberWithInt:i]];

...should do what you want. If this is something you're doing often, you may consider creating a category for constructing an array containing a range.

answered Dec 1, 2009 at 19:50

Skirwan

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5 Comments

Peter Hosey Over a year ago

Don't forget to release the array in the second example, since you have allocked it. (For that matter, why retain it in the first example?)

Skirwan Over a year ago

Lacking context, I imagined a use case that required keeping it around. But yes, in either case the result will need to be released at some point.

user155959 Over a year ago

Careful using convenience constructors in loops. The first example will create 100 temporary arrays, each larger than the last.

retainCount Over a year ago

@Skirwan if you are planning on keeping the object around, use [[NSArray alloc] init] instead - less lines of code.

Motti Shneor Over a year ago

It would be nice to edit and note that the first option is inefficient, and expensive in terms of memory and cpu cycles. You actually allocate a new NSArray 100 times, to create an NSArray of 100 numbers.

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