[iOS] How to mirror app to Apple TV?
All you need to do to cast the app is to:
- Make sure your Apple TV or AirPlay 2-compatible smart TV and iOS device are connected to the same Wi-Fi network.
- Open Control Center:
On iPhone X or later or iPad with iOS 12 or later: Swipe down from the upper-right corner of the screen.
On iPhone 8 or earlier or iOS 11 or earlier: Swipe up from the bottom edge of any screen. - Tap Screen Mirroring.
- Select the device you want to mirror to.
- If asked for a password, please enter the one that appears on the TV screen.
- Open Tabs and enjoy the big screen experience!

For a more detailed explanation, please visit: https://support.apple.com/en-us/HT204289#mirroriOS
If you haven't yet connected your iOS device to a TV yet, please refer to this instruction: https://support.apple.com/en-us/HT208724