The UserNotifications framework (UserNotifications.framework) supports the delivery and handling of local and remote notifications. You use the classes of this framework to schedule the delivery of local notifications based on specific conditions, such as time or location. Apps and extensions also use this framework to receive and potentially modify local and remote notifications when they are delivered to the user’s device.
The NSString class and its mutable subclass, NSMutableString, provide an extensive set of APIs for working with strings, including methods for comparing, searching, and modifying strings. NSString objects are used throughout Foundation and other Cocoa frameworks, serving as the basis for all textual and linguistic functionality on the platform.