The ID Tech audio jack reader is supported as a mobile device accessory on the iOS, Android, Windows mobile, and Blackberry platforms. Many application providers have written and distributed applications for these readers. ID TECH provides a demo application to prove reader functionality/compatibility. Unsure that the audio of your mobile device is turned to the maximum volume.
Please get the UniMag Demo or UniMag Utility for Shuttle, UniMag II and UniMag 1.5 from Apple's app store. Launch the app and select the appropriate reader type. Then you should try to swipe a card.
For the VP3300 Audio Jack, you can download the appropriate USDK from the VP3300 AJ product page.
The Google Play Store has a few apps supporting the Unimag and a Universal SDK Demo supporting the UniPay and other devices.