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
fatal error: file '/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Dev
原文：http://www.cnblogs.com/jgCho/p/4921301.html