How to use Local Notifications for reminders in iOS applications?

Local notifications in the iOS operating system allow an application to send messages and reminders to the user directly from the device itself, without using a remote server or the Apple Push Notification service infrastructure. This is an ideal tool for creating alarms, personal task trackers, and countdown timers that operate completely offline.

The first step in implementing local notifications is requesting the corresponding notification permission from the user. For this, the UNUserNotificationCenter class is used, which requests access to critical types of alerts, such as sound signals, lock screen banners, and application icon badges.

After obtaining the necessary permissions, the developer creates the notification content using the UNMutableNotificationContent class, setting its title, body text, sound, and additional metadata in the form of a userInfo dictionary. Then, a notification trigger is formed, which can be based on a time interval, a specific calendar date, or the user's geographical coordinates.

The final stage is registering the request in the system using the add method of the notification center. The system independently monitors the occurrence of the specified trigger and displays the notification on the device screen, even if your application is currently unloaded from RAM or running in the background.