Can you connect the iPhone 4 to the Acer x110p projector?

Yes, you can connect the iphone 4 to the Acer X110P projector using a compatible adapter. The iphone 4 has a 30-pin dock connector, so you would need a 30-pin to VGA adapter to connect to the projector's VGA port. Once connected, you may need to adjust the projector's input settings to display the iphone's screen.