关于prefix的错误

 类似这样的错误：

fatal error: file '/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator8.1.sdk/System/Library/Frameworks/UIKit.framework/Headers/UITableView.h' has been modified since the precompiled header '/Users/weixuewu/Library/Developer/Xcode/DerivedData/JiaoWuXiTong-grltjakjujuowvcvrkqlqrwpbqfr/Build/Intermediates/PrecompiledHeaders/Pods-AFNetworking-prefix-esbdmbdlgmazudenvxmluxydclkd/Pods-AFNetworking-prefix.pch.pch'
was built

note: '/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator8.1.sdk/System/Library/Frameworks/UIKit.framework/Headers/UITableView.h' required by '/Users/weixuewu/Library/Developer/Xcode/DerivedData/ModuleCache/3HIREQHFIR4KN/UIKit-2M4VYLEDI34V0.pcm'

note: '/Users/weixuewu/Library/Developer/Xcode/DerivedData/ModuleCache/3HIREQHFIR4KN/UIKit-2M4VYLEDI34V0.pcm' required by '/Users/weixuewu/Library/Developer/Xcode/DerivedData/JiaoWuXiTong-grltjakjujuowvcvrkqlqrwpbqfr/Build/Intermediates/PrecompiledHeaders/Pods-AFNetworking-prefix-esbdmbdlgmazudenvxmluxydclkd/Pods-AFNetworking-prefix.pch.pch'

note: please rebuild precompiled header '/Users/weixuewu/Library/Developer/Xcode/DerivedData/JiaoWuXiTong-grltjakjujuowvcvrkqlqrwpbqfr/Build/Intermediates/PrecompiledHeaders/Pods-AFNetworking-prefix-esbdmbdlgmazudenvxmluxydclkd/Pods-AFNetworking-prefix.pch.pch'

1 error generated.

解决方法：

找出note标记的pcm文件地址：/Users/weixuewu/Library/Developer/Xcode/DerivedData/ModuleCache/3HIREQHFIR4KN/UIKit-2M4VYLEDI34V0.pcm
然后删除，重新编译即可

/Users/weixuewu/Library/Developer/Xcode/DerivedData/ModuleCache/3HIREQHFIR4KN/UIKit-2M4VYLEDI34V0.pcm

为缓存文件

Library/Developer/Xcode/DerivedData/ModuleCache

找不到？？

DerivedDate这个文件夹是XCODE的缓存文件夹。你整个删除都没事的。
再来回答你问题：你打开Finder，然后鼠单击顶头的“前往”，然后按你键盘的option键（会出现一个资源库的，你松手又会不见了），你点击资源库，然后依次进入
Developer/Xcode/DerivedData/ModuleCache
就OK了。
或者你打开命令行，然后输入defaults write com.apple.finder AppleShowAllFiles TRUE
killall Finder。回车。就OK了（这个命令是显示OSX系统的隐藏文件的）。其实你就是资源库找错了（这个资源库是隐藏文件来的，你用常规方法肯定找不到