You already have a standalone version of Doc if you have Xcode installed on your system.
B Xcode, go over Help --> Developer Documentation. Label: Option + Command + ?. This will show you the documentation page loaded into Xcode itself. Select the button Homeat the top of the toolbar. It will display a drop-down list of available link libraries. Select the iOS library from the menu. It will show you the page you want.
Xcode, Option + Double-Click on a symbol: . , , . , .