I don't know if this has been mentioned on this forum before, but I'll bring it up again if it hasn't.
My DL came with a 30pin dock simply because I had an old iPad 3.
I now own an iPad mini 2 which stays permanently docked, and is my main source of set break background music.
And a new iPad Air 2 which I traded my ageing iPad 3 on. It is my full time wireless connection to the DL.
Prior to this I have used an old iPhone 4 which I plugged directly into the DL's 30pin dock, but supported by a 2x4 shim of the right thickness to raise the iPhone to the correct height for the dock. It was perfect for supplying background music. I was surprised it worked when I first tried it as I thought I'd need an iPad to be compatible.
Obviously I had zero control of the DL from the docked iPhone. But it was nice to have all 16 channels free to use for actual mixing, instead of 14 channels for mixing and 2 channels sacrificed for set break music.
And with purchase of my 30pin to lightning adapter lead I could plug in anybodies iPhone for music requests also without wasting sometimes needed channels 15 & 16.
Very versatile!
Edit. The point of my post was that a slab of cardboard to raise your iDevice to the right level is a good option. Simple and free