Multidimensional array iteration in objective-c

Question

I want to learn how I can use for-each statements in 2D NSMutableArray. My code is below. It throws an exception at the 3rd (inner-most) for statement. The exception is:

"Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFNumber count]: unrecognized selector sent to instance"

My code:

NSMutableArray* subTryingSet=[NSMutableArray arrayWithArray:[self genSetNumbers:arrRandoms withSize:4]];

for (NSMutableArray* oneRow in subTryingSet) {
    for (NSMutableArray* w in oneRow) {
        for (int i=0;i<w.count;i++) {
            NSLog(@"%d", [[w objectAtIndex:i] intValue]);
        }
    }
}

meronix · Accepted Answer · 2012-04-13 10:01:05Z

3

after a first fast look at your code:

try to change this:

    NSLog(@"%d", [[w objectAtIndex:i] intValue]);

with:

   NSLog(@"%i", [[w objectAtIndex:i] intValue]);

EDIT

"It throws exception at 3th "for statement", so it can't go to slog"

mmm... are you sure that all the objects in oneRow are NSMutableArray?

try to check like this:

for (NSMutableArray* oneRow in subTryingSet) {
  if ([oneRow.class isSubclassOfClass:[NSMutableArray class]]) {
      for (NSMutableArray* w in oneRow) {
        if ([w.class isSubclassOfClass:[NSMutableArray class]]) {
            for (int i=0;i<w.count;i++) {
                NSLog(@"%d", [[w objectAtIndex:i] intValue]);
            }
        }
      }
  }
}

edited Apr 13, 2012 at 10:01

answered Apr 13, 2012 at 9:45

meronix

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3 Comments

lykant Over a year ago

It throws exception at 3th "for statement", so it can't go to nslog.

lykant Over a year ago

ok, you r right meronix. here, w is not an array. i will look why method of genSetNumbers returns "subTryingSet" as one dimensional array. thank you very much. i may ask some questions again about this situation. :)

lykant Over a year ago

actually, the second for must be as "for(NSNumber *w in oneRow)". This was a confusion for me.

user1220713 · Accepted Answer · 2014-09-13 17:24:10Z

You can use this custom objective c method to iterate

-(void)loopMultArray:(NSArray*)a walk:(void(^)(id node,int index,int zindex))n{

    void(^callback)(id node,int index,int zindex) = Block_copy(n);

    NSMutableArray *l=[[[NSMutableArray alloc] initWithObjects:a,nil] autorelease];
    int c=1;
    //This first loop will loop until the count var is stable//
    for(int r=0;r<c;r++){
        //This loop will loop thru the child element list//
        for(int z=0;z<[[l objectAtIndex:r] count];z++){

            callback([[l objectAtIndex:r] objectAtIndex:z],z,r);

            if([[[l objectAtIndex:r] objectAtIndex:z] isKindOfClass:[NSArray class]]){
                [l addObject:[[l objectAtIndex:r] objectAtIndex:z]];
                c++;
            }//IF
        }//FOR
    }//FOR

    Block_release(callback);

}

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