After downloading the latest version of Xcode, I tried to open it.
Xcode greets me with Xcode component installation, stating that Xcode must install the following components before continuing.
So I clicked install and typed in the correct administrative password, but immediately after this, Xcode gives the alert " An unknown error occurred. See the [install log](https://discussions.apple.com/IDEPackageInstallationError_InstallLogLink) for more details."
I didn’t find the log helpful but I did find the solution online, so here it is for anyone else that goes through this:
Optional if you already have Xcode in your applications dir
* Just double click Xcode dmg file ...
* Then window will show Xcode app.
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* Right Click Xcode
* Show Package contents
* Then go to /Contents/Resources/Packages/
* Install MobileDevice.pkg ...
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After installation
* Double click on Xcode app ...
* Just see Xcode is ready ...