Two functions on how to handle zero elements in an NSArray

main.m

#import <Foundation/Foundation.h>
#import <stdio.h>

@interface MyClass : NSObject
@end
@implementation MyClass

// 1. returns the number of non-zero elements (4)
+ (int)numberOfZeroElementsInArray:(NSArray *)array {

 int count = 0;
   for (NSNumber *number in array) {
     if ([number intValue] == 0) {
       count ++;
     }
   }
   return count;
}

// 2. moves the non-zero elements to the beginning of the array (the rest of the elements don't matter)
+ (NSArray *)nonZeroElementsToBeginningForArray:(NSArray *)array {

NSMutableArray *mutableArray = [array mutableCopy];

  int point = 0;
  int count = mutableArray.count;
    NSMutableIndexSet *indexes = [NSMutableIndexSet new];
    while (point < count) {
      NSNumber *number = [mutableArray objectAtIndex:point];
      if ([number intValue] == 0) {
          [indexes addIndex:point];
        [mutableArray addObject:number];
      }
      point ++;
    }

  [mutableArray removeObjectsAtIndexes:indexes];

return [mutableArray copy];
}

@end
  
int main (int argc, const char * argv[])
{
  @autoreleasepool {
    NSArray *array = @[ @1, @0, @2, @0, @0, @3, @4 ];
    printf("%i", [MyClass numberOfZeroElementsInArray:array]);
    printf("\n");

    printf("%s", [[[MyClass nonZeroElementsToBeginningForArray:array] componentsJoinedByString:@","] UTF8String]);

  }
}