Xcode "Device Locked" When iPhone is unlocked

My phone was set to "trust" the Mac, and I still ran into this error with Xcode 6.1.1.

This worked for me:

• unplug device
• quit xcode
• open xcode
• plug in device
• build/run

Did you by chance not "trust" the device? This will prevent it from communicating with xcode even if the device is unlocked.

Update here's a support doc from Apple: http://support.apple.com/en-us/HT5868