Audiobus: Use your music apps together.
What is Audiobus? — Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.Download on the App Store
Audiobus is the app that makes the rest of your setup better.
Using AudioStretch...to modify samples
AudioStretch is designed as a power tool for music transcription and it does a good job at that by changing the playback speed while preserving the pitch or changing the pitch without changing the speed.
But it also is a fun tool to create variations of a sample and in fact creating new samples!
I made some examples using samples from my Memory Collection packs 07 and 10. That can be very useful when that sample you want to use plays a bit too fast or is not the exact pitch you need!
It can easily import and export samples. The modifications can be made in real-time. It also supports Audiobus.