11.3. Filtering and matching with predicates

Now that you know how to reference and access object properties via string-based key paths, it may not surprise you that a layer of other technologies is built on top of this foundation.

Often, when provided with an object, you’ll want to compare it against a certain condition and perform different actions based on the result of the comparison. Similarly, if you have a collection of data, such as an NSArray or NSSet, you may want to use a specific set of criteria to filter, or select, subsets of the data.