How to determine an array index in Objective C?

Question

I have two arrays in Objective C and I need to find what index something is so I can insert it in the same place. For instance, lets say I have a "name array" and an "age array". How do I find out what index "charlie" is in the "name array" so I know where to insert his age in the "age" array?

Thanks

Answer 1

-[NSArray indexOfObject:] would seem to be the logical choice.

Answer 2

In Cocoa, parallel arrays are a path to doom and ruination. You can't use them effectively with Bindings, so you'll have to write a lot of glue code instead, as if Bindings didn't exist. Moreover, you're killing off any future AppleScript/Scripting Bridge support you may intend to have before you even begin to implement it.

The correct way is to create a model class with name and age properties, and have a single array of instances of that class. Then, to find an item by name or age, use NSPredicate to filter the array, and indexOfObjectIdenticalTo: to find the index of each item from the filtered array in the main array.

The difference between indexOfObject: and indexOfObjectIdenticalTo: is that the former will send isEqual: messages to determine whether each object is the one it's looking for, whereas the latter will only look for the specific object you passed in. Thus, you can use indexOfObject: with an object that isn't in the array but is equal to one that is, in order to find the equal object in the array.

Answer 3

You might just want to use an NSDictionary, too, if you're doing lookups based on strings.