First thing's first, you will need a MIDI keyboard. It doesn't matter what brand, size and features it's got as long as you have a working MIDI keyboard. I got two MIDI keyboards. One is Evolution MK249C which I bought from carboot sale 8 years ago. Then just recently on my 40th birthday, our friends Mark and Chris gave us this M-Audio KeyStudio MIDI keyboard. I will do a comparison of the two keyboards in the near future. The other thing that you will need is an iPad or iPhone. Because we will be using Garageband for our MIDI keyboard. Now, the last thing that you will be needing and it's the most important one, the adapter. I thought I can buy any as long as it's the right pins for the ipad/iphone and convert to USB but I was wrong. There are specifics to it.
Right, let's take my phone and ipad as an example. Im using iPhone 7 and iPad Pro. Both uses lightning connectivity or jack. So I would need a lightning to USB adapter. Went to nearest Apple store, asked around, some staff are very helpful but there's one guy who's a bit snobbish. Went to him to pay actually but he was busy talking to his radio and then after he finished talking or reporting something he went back straight to his iPad and did'nt say a word to me. So I looked for another person and this time a young lady. She was very helpful. Because when I told her about the plan of buying that lightning to USB camera adapter that I will be using it for my MIDI keyboard, she already mentioned to me that there are some issues that they encounter. She said that it might not work because it depends on what sort of MIDI keyboard Im using. So I asked her if I can return the product if it won't work and she said yes, there's 14-day return policy. All I need is the receipt and the product as well as the box.
Went home and tried the lightning to USB camera adapter and it didn't work. It says the device uses too much power. I tried looking around for a solution. Good thing my other MIDI keyboard (Evolution MK249C) got a power input. So, I tried looking for a suitable power supply. It says 9-12 volts. The only problem now is the polarity. I tried my Zoom G1xOn adaptor because it's 9 volts but it didn't work. So I looked for my old Digitech multieffects power supply and it worked on that one. Connect it to my ipad and iphone and it worked. But I wasn't satisfied, I thought that I really wanted the ipad/iphone to work without plugging my MIDI keyboard to a power supply. So I can also use my M-Audio KeyStudio because this MIDI keyboard doesn't have a power input. Good thing, my good friend Creed on YouTube, saw one of my post about the lightning splitter for my iTrack pocket that didn't work, and he mentioned to me to buy a lightning to USB 3 camera adapter with the power port. Because he had similar problem. That's when I decided to return and change my light to USB adapter.
After I changed it, it was perfect. No need for power supply and it work for my iPad and iPhone as well as to both of my MIDI keyboards, the Evolution MK249C and M-Audio KeyStudio. Im very happy now.
Note: Always buy original apple accessories to avoid incompatibility issues. But also buy the right accessory.