How do you implement background fetch and background refresh in IOS?

To implement background fetch and background refresh in iOS, you need to follow the steps outlined below:

1. Enable Background Modes: In your Xcode project, go to the "Capabilities" tab and enable the "Background Modes" option. Then, check the "Background fetch" and "Remote notifications" checkboxes.

2. Register for Background Fetch: In your AppDelegate.swift file, add the following code in the `didFinishLaunchingWithOptions` method to register for background fetch:

```swift
UIApplication.shared.setMinimumBackgroundFetchInterval(UIApplication.backgroundFetchIntervalMinimum)
```

3. Implement Background Fetch Handler: Add the following method in your AppDelegate.swift file to handle background fetch:

```swift
func application(_ application: UIApplication, performFetchWithCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
// Perform your background fetch tasks here

// Call the completion handler when finished
completionHandler(.newData) // or .noData or .failed
}
```

4. Handle Background Refresh: To implement background refresh, you need to handle remote notifications. Implement the following method in your AppDelegate.swift file:

```swift
func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any], fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
// Process the received remote notification

// Call the completion handler when finished
completionHandler(.newData) // or .noData or .failed
}
```

5. Configure Background Modes in Info.plist: Open your Info.plist file and add the following keys:

- `UIBackgroundModes` with an array value.
- Inside the array, add two items:
- `fetch` for background fetch.
- `remote-notification` for background refresh.

6. Testing: To test background fetch, run your app on a device or simulator, then press the home button to put the app in the background. After a while, the system will wake up your app in the background and call the background fetch handler method.

To test background refresh, you can send a remote notification to your app using a service like Firebase Cloud Messaging (FCM) or Apple Push Notification Service (APNS). When the notification is received, the system will wake up your app in the background and call the remote notification handler method.

By following these steps, you can successfully implement background fetch and background refresh in your iOS app.