系統環境：Lion正式版10.7.1(build 11B26)
Xcode 4.1.1 (build 4B110)
PS：Xcode 4.1和 4.1.1的區別在於安裝界面，本身內容沒有變化，build號4B110就是4.1.1的
在全新安裝Lion之後，App Store下載安裝了Xcode，發現並沒有附帶iOS和Mac OS X Lion的編程參考文檔(Library)。
在Preferences-->Documentation中點擊Check and Install Now
iOS 4.3 Library (v. 38.103)
API reference and conceptual documentation for iOS 4.3.
Copyright © 2011 Apple Inc. All rights reserved.
Feed: http://developer.apple.com/rss/com.apple.adc.documentation.AppleiPhone4_3.atom
Web Root URL: https://developer.apple.com/library/ios/
Identifier: com.apple.adc.documentation.AppleiOS4_3.iOSLibrary
Installed Location: /Developer/Platforms/iPhoneOS.platform/Developer/Documentation/DocSets/com.apple.adc.documentation.AppleiOS4_3.iOSLibrary.docset
Mac OS X 10.7 Core Library (v. 410.26)
Copyright © 2011 Apple Inc. All rights reserved.
Feed: http://developer.apple.com/rss/com.apple.adc.documentation.AppleLion.atom
Web Root URL: https://developer.apple.com/library/etc/redirect/xcode/mac/548/
Identifier: com.apple.adc.documentation.AppleLion.CoreReference
Installed Location: /Developer/Documentation/DocSets/com.apple.adc.documentation.AppleLion.CoreReference.docset
根據得到的版本號和feed地址，使用safari或者firefox打開頁面選擇最新的版本下載，解壓縮到安裝目錄，如圖中所示
然後要修改解壓出來的docset所有者信息和文件屬性
sudo chown -R -P _devdocs:wheel com.apple.adc.documentation.AppleLion.CoreReference.docset
sudo chmod 775 com.apple.adc.documentation.AppleLion.CoreReference.docset
sudo chown -R -P _devdocs:wheel com.apple.adc.documentation.AppleiOS4_3.iOSLibrary.docset
sudo chmod 775 com.apple.adc.documentation.AppleiOS4_3.iOSLibrary.docset
然後重新啟動Xcode，就能查看文檔了
