Ethan Allen Ethan Allen - 6 months ago 15
Objective-C Question

What is an easy way to break an NSArray with 4000+ objects in it into multiple arrays with 30 objects each?

What is an easy way to break an NSArray with 4000 objects in it into multiple arrays with 30 objects each?

So right now I have an NSArray *stuff where [stuff count] = 4133.

I want to make a new array that holds arrays of 30 objects. What is a good way to loop through, breaking *stuff into new 30-object arrays, and placing them inside of a larger array?

Obviously the last array won't have 30 in it (it will have the remainder) but I need to handle that correctly.

Make sense? Let me know if there is an efficient way to do this.

Answer

Off the top of my head, something like (untested):

NSMutableArray *arrayOfArrays = [NSMutableArray array];

int itemsRemaining = [stuff count];
int j = 0;

while(itemsRemaining) {
    NSRange range = NSMakeRange(j, MIN(30, itemsRemaining));
    NSArray *subarray = [stuff subarrayWithRange:range];
    [arrayOfArrays addObject:subarray];
    itemsRemaining-=range.length;
    j+=range.length;
}

The MIN(30, i) takes care of that last array that won't necessarily have 30 items in it.