应用程序/Xcode.app右击显示包内容->
/Applications/Xcode.app/Contents/Developer(开发者)/Platforms(平台)/iPhoneOS.platform/Developer(开发者)/SDKs(开发
包)/iPhoneOS.sdk/System(系统)/Library(库)/Frameworks(框架)/Foundation.framework/Headers(头文件)

应用程序/Xcode.app右击显示包内容->
/Applications/Xcode.app/Contents/Developer(开发者)/Platforms(平台)/iPhoneOS.platform/Developer(开发者)/SDKs(开发
包)/iPhoneOS.sdk/System(系统)/Library(库)/Frameworks(框架)/Foundation.framework/Headers(头文件)