Xcode docsets can be downloaded from Xcode’s Preferences > Downloads > Documentation. After the download finishes, open Dash’s Preferences > Docsets and click the Rescan button at the bottom right. Dash will then find the new docsets that Xcode installed.

这是正确的打开方式,但是在大陆,用xcode下载实在太慢了,所以尝试绕开xcode来下载。在https://developer.apple.com/library/downloads/docset-index.dvtdownloadableindex可以找到iOS8.1和OSX10.10的文档下载地址,是dmg格式,默认安装到/目录下(com.apple.adc.documentation.AppleiOS8.1.iOSLibrary.docset和com.apple.adc.documentation.AppleOSX10.10.CoreReference.docset)。需要手动复制到~/Library/Developer/Shared/Documentation/DocSets/。然后回去dash用Rescan就可以看到了。下载建议用迅雷,可以满速。


更新2015/1/29

命令行操作,以iOSDocset为例

hdiutil attach -noautoopen 031-07735-A.dmg
pkgutil --expand /Volumes/iOSDocsetCD/iOSDocset.pkg ~/Downloads/iOSDocset
mkdir -p ~/Library/Developer/Shared/Documentation/DocSets/
tar xf ~/Downloads/iOSDocset/Payload -C ~/Library/Developer/Shared/Documentation/DocSets/