Syntorial – synth programming tutorial app finally comes to iOS. I used to play with it while it was desktop and I need to say that this is the best tool to learn synthesis.
The app itself is free with few lessons to get a sense of an app. To open all the tutorials it is cheaper to pay through developers website and get desktop and VST version – syntorial.com + tutorials.
For example in UK IAP is 99GBP (apprx 150 USD) while on the website is 129$