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# init(center:radius:identifier:)

Creates and returns a region object defining a circular geographic area.

```
init(center: CLLocationCoordinate2D, radius: CLLocationDistance, identifier: String)
```

## Parameters

`center`

The center point of the geographic region to monitor.

`radius`

The distance (measured in meters) from the center point of the geographic region to the edge of the circular boundary.

`identifier`

A unique identifier to associate with the region object. You use this identifier to differentiate regions within your app. This value can’t be `nil`.

## Return Value

An initialized region object.

## Discussion

When defining a geographic region, remember that the location manager doesn’t generate notifications immediately upon crossing a region boundary. Instead, it applies time and distance criteria to ensure that the crossing is intentional and needs to trigger a notification. So choose a center point and radius that are appropriate and give you enough time to alert the user. For more information, see the information about region monitoring in [Location and Maps Programming Guide](https://developer.apple.com/library/archive/documentation/UserExperience/Conceptual/LocationAwarenessPG/Introduction/Introduction.html#//apple_ref/doc/uid/TP40009497).

---

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