Where and how is a data collection usually stored in an application?

In iOS, data collections are usually stored in the following locations:

• UserDefaults — for small settings and simple data.
• File system (Documents, Caches) — for storing files and large volumes of data.
• Core Data — for complex structured data with query and relationship management capabilities.
• Realm or other third-party databases — for convenient and fast data storage.

The choice depends on the volume and structure of the data. For example, for a list of notes, Core Data is preferable, while for settings, UserDefaults is suitable.