i bought the UNO board , and i have a mac os x 10.12.1 and also i installed Arduino IDE both version of 1.6.13 and 1.6.14(which is beta right now) , and i try so many ways such as Reinstall the driver and so much more links on the net , but none of them works for me !!
do anyone know what is the problem that i'm experiencing !?
You can download below driver and install. I tried and it worked for me 
Link:
http://www.ftdichip.com/Drivers/VCP/MacOSX/FTDIUSBSerialDriver_v2_2_14.dmg
What serial adapter is on the board you're using? Read the part number off the black chip near the USB port. Clones often don't have the same serial adapter as the official boards, so you need to download drivers for them separately.
Sounds like the problem I was having with my UNO clone. This page has drivers for earlier versions of Mac OS X, but maybe they will work with Sierra. Worth a shot.
On OSX High Sierra I installed such package and also renamed this file:
/System/Library/Extensions/AppleUSBFTDI.kext