Question

I have several custom objects in an NSArray, I need to search through all the objects and fnd the index of the object that has a property which matches a string.
Should I be using a for each loop? I need it to be relatively fast to search each time a new character is entered in a textfield.

Answer 1

NSPredicate is neat, but overkill (and it won’t give you the index of the found object; just the object itself).

The paired array approach, which will work, feels odd to me (probably because it’s using a paired array).

I would either use a for() loop (and break; when I found what I was looking for), or use a block enumerator:

__block NSInteger indexOfMatchingObject = NSNotFound;
[myArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
  if ([[obj property] doesWhatImLookingFor]) {
    indexOfMatchingObject = idx;
    *stop = YES;
  }
}];

Or a slightly different variant:

NSInteger indexOfMatchingObject = [myArray indexOfObjectPassingTest:^(id obj, NSUInteger idx, BOOL *stop) {
  return ([[obj property] doesWhatImLookingFor]);
}];