I have a guitar diagram app for Android that I am porting to iOS. Android has a embedded midi synthesizer (sonivox), so I can generate midi files and let Android handle the playback.
Is there a way to do this on iOS? Or are there very lightweight embeddable synths for iOS?
Since iOS 5 there's now the AUSampler audio unit for which you can load a sound bank (apple preset and soundfonts) and then control the sampler/synth via MIDI messages.
Seee this example app: https://developer.apple.com/library/ios/#samplecode/LoadPresetDemo/Listings/ReadMe_txt.html
It works great!