[sunny]

Hi Zhao

No I use this adaptater wich is a little different
– http://www.apple.com/shop/product/MK0W2AM/A/lightning-to-usb-3-camera-adapter

And this is the problem because the iPhone 5 is not in the compatibility list of this adapter (only iPads)…

But this is what I tried: I upgraded my iPhone 5 to latest IOS (9.3.3)
And.. problem is solved !
The xkey is recognized and I can use it with all compatible apps

So the USB3/lightning adapter need IOS 9 to be compatible with iPhone5

Thanks again and I hope it helps
Have fun with xkey!