Follow the steps to cast Twitch App through Chromecast:

1- Setup: Make sure your Chromecast-enabled device and iOS device are connected to the same Wi-Fi network.

2- Install Twitch App: Download and install the Twitch app from the App Store.

3- Open Twitch App: Open the Twitch app and log in to your Twitch account.

4- Choose a Stream: Browse and select the stream you want to watch.

5- Casting: Look for the casting icon within the Twitch app. This icon is usually located in the top-right corner of the stream player, represented by the Chromecast symbol.

6- Choose Chromecast: Tap on the casting icon, and a list of available devices to cast to will appear. Select your Chromecast-enabled device from the list.

7- Start Casting: After selecting your Chromecast device, the stream should start playing on your TV

OR

1- Setup: Make sure your Chromecast-enabled device and iOS device are connected to the same Wi-Fi network.

2- Browse the Twitch website: Through Cast for the Chromecast app’s browser navigate to www.twitch.com.

3- Play your Stream: Find and play your stream. The app will auto-detect the URL to cast

4- Select a detected link: From the list of available links tap on the link you want to cast.

5- Choose Chromecast: Tap on the casting icon, and a list of available devices to cast to will appear. Select your Chromecast-enabled device from the list.

6- Start Casting: After selecting your Chromecast device, the stream should start playing on your TV.