xcode下载

http://adcdownload.apple.com/Developer_Tools/Xcode_7.3.1/Xcode_7.3.1.dmg

http://adcdownload.apple.com/Developer_Tools/Xcode_8.1/Xcode_8.1.xip

https://developer.apple.com/download/  然后点击下面的more

xip双击就行

如果报错：xip cpio read error

解决：更新系统

参考

http://stackoverflow.com/questions/10335747/how-to-download-xcode-4-5-6-7-and-get-the-dmg-file