split array of objects into groups of 4 - ios

Question

How do you split an array of objects into an array of array of objects?

say I want to split into groups of 4, how do I do that?

[a,b,c,d,e,f,g,h] => [a,b] [c,d] [e,f] [g,h]

or maybe if I specify that I want to split into groups of 3, then the result should be [a,b,c], [d,e,f], [g,h]

it should also work if h doesn't exist.

Murali · Accepted Answer · 2012-11-21 05:29:21Z

2

Try this logic.....

NSArray *arr = [[NSArray alloc]initWithObjects:@"One",@"Two",@"Three",@"Four",@"Five",@"Six",@"Seven",nil];
NSMutableArray *arrNew = [[NSMutableArray alloc]init];
int numberofSubArrs = 3; // change this to check the logic
for (int i=0; i<numberofSubArrs; i++) {
    NSMutableArray *arrrr = [[NSMutableArray alloc]init];
    [arrNew addObject:arrrr];
}
int m = 0;
for (int k=0; k<[arr count]; k++) {
    [[arrNew objectAtIndex:m]addObject:[arr objectAtIndex:k]];
    m++;
    if (m == numberofSubArrs) {
        m=0;
    }
}
int g=0;
int p=0;
while(p<[arr count]) {
    for (int z=0; z<[[arrNew objectAtIndex:g] count]; z++) {
        [[arrNew objectAtIndex:g] replaceObjectAtIndex:z withObject:[arr objectAtIndex:p++]];
    }
    g++;
}
NSLog(@"Required Array is:%@",[arrNew description]);

edited Nov 21, 2012 at 5:29

answered Nov 20, 2012 at 12:40

Murali

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1 Comment

user1372829 Over a year ago

have you actually tried this? where do you specify how many names you want to split into per array into the main array

tkanzakic · Accepted Answer · 2012-11-21 08:12:00Z

1

Try this as a starting point:

NSArray *array = [NSArray arrayWithObjects:@"a", @"b", @"c", @"d", @"e", @"f", @"g", @"h", nil];
NSMutableArray *manyArrays = [NSMutableArray array];
int numberOfElementsInSubArrays = 2;
int numberOfSubArrays = ceil((float)[array count] / (float)numberOfElementsInSubArrays);
for (int i = 0; i < numberOfSubArrays; i++) {
    NSMutableArray *subArray = [NSMutableArray array];
    for (int j = 0; j < numberOfElementsInSubArrays; j++) {
        if (i*numberOfElementsInSubArrays+j < [array count]) {
            NSLog(@"Array: %d Value:%@", i, [array objectAtIndex:i*numberOfElementsInSubArrays+j]);
            [subArray addObject:[array objectAtIndex:i*numberOfElementsInSubArrays+j]];
        }
    }
    [manyArrays addObject:subArray];
}

edited Nov 21, 2012 at 8:12

answered Nov 20, 2012 at 12:38

tkanzakic

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2 Comments

user1372829 Over a year ago

something similar, but instead of setting of number of subarrays, only just specifying the number of elements in a group

tkanzakic Over a year ago

try it now, I change it to set the number of elements in a group instead of the number of groups

Alejandro Benito-Santos · Accepted Answer · 2012-11-20 12:31:46Z

0

Give this a try.

NSMutableArray *splitted = [NSMutableArray array];    
id firstItem, secondItem;
for (NSInteger i=0; i <= [originalArray count]-1; i+=2) {
        @try {
            firstItem = [originalArray objectAtIndex:i];
            secondItem = [originalArray objectAtIndex:i+1];
        }
        @catch (NSException *exception) {
            secondItem = [NSNull null];
        }
        @finally {
            [splitted addObject:@[firstItem,secondItem]];
        }
 }

answered Nov 20, 2012 at 12:31

Alejandro Benito-Santos

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