解决 升级xcode8 后 连接手机出现Could not connect to lockdownd. Exiting.
升级xcode8后，ideviceinstaller命令运行报错：
Could not connect to lockdownd. Exiting.
解决方法：
sudo chmod -R 777 /var/db/lockdown/
或者一次性解决问题：
brew uninstall ideviceinstaller
brew uninstall libimobiledevice
brew install --HEAD libimobiledevice
brew link --overwrite libimobiledevice
brew install ideviceinstaller
brew link --overwrite ideviceinstaller