Xcode 10.2 Failed to Run App on Simulator with iOS < 10

This is a known bug affecting iOS 8.x and 9.x. You can work around it by creating /usr/lib/swift directories in the relevant simulator runtime root.

Downloaded simulator runtimes are located in /Library/Developer/CoreSimulator/Profiles/Runtimes.

For example, to fix the iOS 9.3 simulator:

sudo mkdir '/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 9.3.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift'

Me also got the same problem when run in iOS 9.0 simulator.

From https://developer.apple.com/documentation/xcode_release_notes/xcode_10_2_1_release_notes

Simulators for iOS 9.3 and earlier might fail to launch Swift apps with the message: “dyld: Library not loaded: /usr/lib/libauto.dylib”. (49326587)Workaround: Run the following command in Terminal for the relevant version of iOS:

sudo mkdir '/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 9.3.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift'

For this apple given above solution in that link.

Simply

--> open Terminal

--> Type this line with your required version (In my case i changed into iOS 9.3 to iOS 9.0)

Ex: sudo mkdir '/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 9.0.simruntime/Contents/Resources/RuntimeRoot/usr/lib/swift'

--> Enter password

--> Now clean Xcode and run again

This above solution worked for me.

This seems like an iOS Simulator bug. I see this happening on simulators with iOS 12.0 but not on those with 12.4.