I am trying to install Sims 3, but it opens a window saying that "The following disk images couldn't be opened because the image data was corrupted." What can I do to resolve this issue?
The error message means that the downloaded file is corrupt and can't be opened.
Re-download it and try opening it again. If it fails again, make sure that the download isn't being interrupted.
If you can obtain a checksum for the file, you can check it against your download by running
openssl sha1 ~/path/to/download which will show the checksum for your download. Comparing the results should show if the file you downloaded matches what you should expect to download.
I just opened by Disk Utility and Select the mounted Xcode Disk. Finally, right-click and choose Open in Finder. Then, move the Xcode to application.