CadRemote to use, you need a free program for your PC or Mac may require that you download from the website developer Maiden Inc.. That connects your iPhone or iPod touch in the same WiFi network with your computer. Then you can use the app as you mouse for drawing, such as AutoCad, use.
By a finger on the screen to keep tilting the iPhone, you can orbit movements. By the image swipe, and you pan with your finger along the right side, you can zoom in and out. Further hotkeys are at the bottom to activate the cursor, commit, aid, rendering and maximum zoom.
Download: CadRemote (free)