Creating an array from properties of objects in another array

Question

Is there any convenient way to take an array/set of objects and create a new array/set containing some property of each item in the first array?

For example, an array co

Answer 1

This will return an array containing the value of licensePlate from each item in the myCars array:

NSArray *licensePlates = [myCars valueForKeyPath:@"licensePlate"]

If you want only unique items (for example), you can do something like this:

NSArray *licensePlates = [myCars valueForKeyPath:@"@distinctUnionOfObjects.licensePlate"];

For more possibilities, see the Collection Operators documentation in the Key-Value Coding Programming Guide.