NSArray * b = @[@5,@2,@3,@1,@8]; NSMutableArray *a = @[].mutableCopy; for (int i=0; i<11; i++) { a[i] = @0; } for (NSNumber *num in b) { int index = [num intValue]; if(a[index]){ a[index] = @([a[index] intValue] + 1); } else { a[index] = @0; } } for (int i = 0; i<a.count; i++) { if([a[i] intValue]>0){ NSLog(@"%d",i); } }