DTAssetProviderService could not start DTXConnection with Simulator 'iPhone 6s Plus'. Check the system log for errors. 他给我这个 提示
重启模拟器，重启Xcode，重启mac机器
http://stackoverflow.com/questions/36200318/dtassetproviderservice-could-not-start-dtxconnection-with-simulator
Killing the simulator and restarting it from Xcode helped me.