iPhone allows users to change the sound produced after posting message to Facebook using the Sound Settings.
Step 1: Press the menu button on iPhone to access the Home screen.
Step 2: Tap the settings icon on the iPhone and in the Settings screen scroll down to Sounds option.
Step 3: In the Sounds screen, navigate to Sounds and Vibrations Patterns section and tap the Facebook Post.
Step 4: Now you can pick Sounds other than default Swish sound for the Facebook Post.