You can connect your iOS or Android smartphone to your PS4 using the PlayStation app. In this case, the console can be controlled via a smartphone or used as a second screen (if the game supports dual-screen mode). You can also connect a USB flash drive to your PS4 to play media files on your console or copy important data to the drive.
Steps
Part 1 of 2: How to connect a smartphone that has the PlayStation app

Step 1. Install the PlayStation app on your smartphone
This app can be downloaded for free from the Apple App Store or Google Play Store. It supports iOS and Android smartphones

Step 2. Connect your console and smartphone to the same network
- The console can be connected to a wireless network or with an Ethernet cable.
- To find out which network your console is connected to, open the Settings menu and select Network. Now connect your smartphone to the same network.

Step 3. Open the Settings menu on your PS4
It's in the right corner of the top menu. Press Up on the PS4 main menu to go to the top menu

Step 4. Select "PlayStation App Connection Settings"
Select Add Device. A code will be displayed on the screen

Step 5. Launch the PlayStation app on your smartphone
You do not need to sign in to your PlayStation Network to access your PS4

Step 6. Tap "Connect to PS4"
This option is located at the bottom of the screen

Step 7. Tap the PS4 name
It will appear on the Connect to PS4 screen; underneath you will find the word "Enabled". If there is no console name, make sure the console and smartphone are on the same network, and then click Refresh

Step 8. Enter the code that appears on the PS4 screen
This eight-digit code will allow you to connect your smartphone to your PS4

Step 9. Connect to PS4
When you enter the code, the smartphone will immediately connect to the PS4. Now you can control the console via your smartphone

Step 10. Activate console management
To do this, click "Second Screen".
- The smartphone will turn into a controller, which means it can be used to navigate the console menus. You can also control games using your smartphone.
- Swipe through the menu on your smartphone screen, and then tap the option you want to make a selection.

Step 11. Activate the second screen function (if dual screen mode is supported by the game)
In some games, the smartphone can be used as a second screen. In this case, tap the number “2” at the top of the smartphone screen

Step 12. Use your smartphone as a keyboard to the console
To do this, click on the keyboard-shaped icon. The smartphone's onscreen keyboard will make it easier to enter text (compared to using a controller)

Step 13. Turn off your PS4
This can be done using a smartphone. To do this, close the Second Screen controller and then click Power. If the Power function turns off the console by default, the PS4 will turn off; if this function puts the console into standby mode, the PS4 will go into standby mode
Part 2 of 2: How to Connect a USB Flash Drive

Step 1. Format your USB drive so that it can work with PS4
- A USB storage device is used to play media files or to copy important data to it. The drive must be formatted for the console to recognize it. Keep in mind that by default, most USB drives can work with game consoles; also remember that formatting will destroy all files on the flash drive.
- Right-click on the flash drive that is connected to your computer, click "Format" and then select "FAT32" or "exFAT".

Step 2. Create folders "MUSIC" (for music), "MOVIES" (for movies) and "PHOTO" (for photos) on the drive
These folders need to be created in the root directory of the USB drive

Step 3. Copy the files to be played on the console to the appropriate folders
For example, copy the music files to the "MUSIC" folder (and so on)

Step 4. Connect USB storage to PS4
Note that large (wide) drives are difficult or impossible to fit into the console

Step 5. Launch the Media Player application
It plays music and video files.
This application is located in the "Applications" section

Step 6. Select a USB drive to view its contents
Do this when launching the Media Player application

Step 7. Find the song or video you want
Look for them in the folders you created

Step 8. Play the song or video
As soon as you select a song (or video), it starts playing. Press the "PlayStation" button to go to the PS4 main menu; the music will play in the background

Step 9. Copy your save game to a USB drive
- The USB stick can be used to store backups of your game saves.
- Open the Settings menu and select Manage Application Saved Data.
- Now select "Saved data in system storage" and find the data you want.
- Tap Options> Copy to USB.
- Select the files you want and click "Copy".

Step 10. Copy screenshots and game clips to USB stick
- The flash drive can be used to store game screenshots and clips.
- Launch the Capture Gallery app. It's in the Library.
- Find the files you want.
- Tap Options> Copy to USB.
- Select the files you want and click Copy to copy the files to your flash drive.