Midi on the iPhone?
Roni Music, the same developer responsible for the Amazing Slow Downer app, makes an app named Sweet MIDI Player. This is a free app that works the same way as the free Amazing Slow Downer Lite version: there are sample tracks, and you can try it out on up to a quarter of the loaded track. If you like it, you can do an in-app purchase for the full version of the app for $14.99. There may be other apps that will work if you just want to play midi files, and don't need the other features to be accessible.
What a potentially fun app! but how does one do the in-app purchase using VoiceOver to get the full power of the app?
The buttons for "Help" and "Settings" only appear to the left and right of the four standard button options at the bottom of the screen for this app when your iPhone is held in landscape mode. Check your status bar to make sure that your orientation lock is not on, so you can display the app in landscape mode. If orientation lock is on, bring up the Display Center with a three finger swipe up and double tap to toggle "Lock Orientation" off. I've heard that with the iPhone 6 Plus, you may have to turn off Display Zoom to rotate the screen, but I don't have this model iPhone, and I don't use the zoom feature, so I can't verify this.
In landscape mode, do a four-finger tap on the bottom half of the screen to move to the last element, which will be the "Settings" button at the bottom right corner. Double tap on "Settings" and the first item will be for purchasing/restoring in-app purchase. Double tap the "Done" button in the top right corner to exit Settings. You can also review the information about Sweet Midi Player from the "Help" button before deciding to purchase.
Thank you. I never thought of changing to landscape mode as I am allergic to it. (huge grin)