USB Music Smartphones - Apple iPhones
Android is "open source." Code is freely shared with a large app developer and phone manufacturer community. Apple, on the other hand, manufacturers their phones. Apple has a developer community too, but Apple's business model is more proprietary than Android.
Apple's proprietary lightning bus and power connection along with their requirement of an Apple specific chip means downloading high resolution music files requires use of special cable (the Apple CCK) and apps such as ONKYO's HF Player or the FLAC Player app.
The Apple cables that use the Lightning Device Mode Chip do not allow High res audio output without the help of an App like ONKYO HF Player or FLAC Player.
Using an Apple Camera Connection Kit (CCK)
Apple Camera Connection Kit
Some devices require the use of an Apple CCK and a Dragon USB cable. You cannot connect products like the Chord Mojo or Chord Hugo directly to Apple iPhones or iPads because these devices do not have Apple Authenticity Chips.
Amps & Dacs need an Apple authenticity chip to connect directly to Apple iPhones and iPads.
For this reason you need the help of an Apple CCK which allows you to connect and pull data from your Apple iPhone or iPad to the audio device with no authenticity chip.
The Apple CCK will pull music from your Apple iPhone or iPad.