Challenge: Upgrade a placed building

With the knowledge you’ve learned, you’re ready for your first challenge! Try extending the building behavior to upgrade a placed building. Here’s how the logic could work:

1. The player single taps on a placed building to enter upgrade mode. The UI icons change as a result.
2. The player has to single tap one of the new UI icons to upgrade the building.
3. The placed building’s model is now swapped out with the upgraded model.
4. The game exits upgrade mode.

Have fun with the challenge and be sure to reach out on Twitter to show me what you’ve made!