You can use your phone as a keyboard.
Previously it was a serious hassle to enter long messages using the analogue sticks on PS3, with only an ugly wireless keypad peripheral available to ease the pain. Thankfully, PS4 delivers a choice of interfaces and, as well as a helpful touchpad input, allows you to use the PlayStation App as a second screen for text entry. With your phone and PS4 on the same Wi-Fi network you can pair them via the PlayStation App connection settings on the PS4. Then, with both logged in to the same PSN ID, select the second screen option, choose the keyboard icon at the top left and, as if by magic, PlayStation messaging becomes fun again.