Sometimes after updating Xcode or mac OS to latest version, playground may not work as intended. After typing the code in playground when we click the run button, the playground will end up showing Running myPlayground… and will not execute the code. This may be due to a Xcode process that doesn’t quit even after terminating the Xcode. In order to make this playground work, open the Activity Monitor and search for the task com.apple.CoreSimulator.CoreSimulatorService. Now, press the quit button. If its not getting quit, press the forceQuit button. Now quit from Xcode and launch it again. Hopefully playground should work good.