Unable to boot device because it cannot be located on disk
I was able to resolve the issue running xcrun simctl erase all in Terminal.
xcode9.1
warning: ‘characters’ is deprecated: Please use String or Substring directly
Swift 4 introduced changes on string API. You can just use !stringValue.isEmpty instead of stringValue.characters.count > 0 for more information you get the sample from here for e.g let edit = “Summary” edit.count // 7