第二版第8章第二节的NSConcreteNotification头文件问题

Mail的头文件里面没有这个类

iPhone:~ root# grep -r NSConcreteNotification /System/Library/
Binary file /System/Library/Caches/com.apple.dyld/dyld_shared_cache_arm64 matches
Binary file /System/Library/Caches/com.apple.dyld/dyld_shared_cache_armv7s matches
grep: /System/Library/Frameworks/CoreGraphics.framework/Resources/libCGCorePDF.dylib: No such file or directory
grep: /System/Library/Frameworks/CoreGraphics.framework/Resources/libCMSBuiltin.dylib: No such file or directory
grep: /System/Library/Frameworks/CoreGraphics.framework/Resources/libCMaps.dylib: No such file or directory
grep: /System/Library/Frameworks/System.framework/System: No such file or directory

貌似也没什么文件,在xcode帮助里也搜不到,求指点迷津

这不都已经找到了么?

IOKit.framework 这个?