- Open Xcode -> Preferences -> Components.
- Open the Console App, clear the console.
- Go back to the Xcode preferences. Start the simulator download, then cancel it.
- Now in the Console, you will see something about the cancellation with the download URL.
- Copy the URL from the Console, download it.
- Copy this file to ~/Library/Caches/com.apple.dt.Xcode/Downloads.
    - If `Downloads` did not exist, create a new `Downloads` directory.
    - If `Downloads` exists, remove all `*.dvtdownloadableindex` files under it.
- Open Xcode -> Preferences -> Components, start the simulator download again, it should find the file you downloaded and install it.