Though not a guitar app as such, it has an interesting approach to chords and progression. It’s design is clean and attractive but it
is iOS 8 only. The developers say….
“SoundPrism Electro Mini is a musical instrument for your iPhone or iPod which makes it easy to come up with great chord progressions.
Play full arrangements of bass, harmony and melody with just one tap, making it an indispensable tool for songwriters or electronic musicians looking to add powerful chord progressions to their tracks.
* New sound engine with rock-solid polyphony and great-sounding effects. SoundPrism Electro’s new sounds are hand-crafted by Swiss sound designer Oliver Imseng to work beautifully with each other.
* Innovative and improved chord input system: effortlessly play inversions and chord progressions while focusing on your track, not on the music theory behind it.
* A ribbon controller for live manipulation of the built-in effects.
* New interactive tutorial system: SoundPrism Electro Mini walks you through its interface and teaches you how to play.
* Supports Audiobus including state saving.
* Supports Core MIDI”
Its available here…..