Under what conditions does an application transition from active to inactive?

An iOS application transitions from the active state to the inactive state in the following cases:

• When system notifications appear, such as an incoming call or SMS.
• When the screen lock mode is activated.
• When system dialogs are launched, such as permission requests.

In the inactive state, the application does not receive user input events but is not fully suspended yet. This is an intermediate state before transitioning to the background or back to the active state.

Lifecycle methods related to this transition, for example, in AppDelegate:

• applicationWillResignActive(_:) — called when transitioning from active to inactive.

This is important for pausing animations, timers, and other tasks that require active user interaction.