FabFilter has just announced that FabFilter Saturn 2 is now also available as AUv3 plug-in on iOS, saying:
You can start using your favorite distortion and saturation plug-in in popular host apps such as AUM, GarageBand and Cubasis, just like all FabFilter Pro plug-ins.
In addition, FabFilter has updated all FabFilter AUv3 plug-ins for iOS with bug fixes and small improvements.
All FabFilter AUv3 plug-ins for iOS, including Saturn 2, are available exclusively via the App Store (iPad only): apps.apple.com/us/developer/fabfilter/id421796789
Find Saturn 2 in the KVR Marketplace