What should I do if the message of Apple's mobile phone is delayed?

Apple mobile phone message delay can open the background refresh, the method is as follows:

Tools/materials: iPhone 12, IOS 14.4.2, settings 1.0.

1. Click the settings icon on the home screen.

2. In the setting interface, click General Options.

3. In the common interface, click here to refresh the background App.

4. In the background application refresh settings interface, click here to view the background application refresh options.

5. Refresh the application in the background, and open WLAN and cellular network here.