强大的谓词,官方文档
https://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/Predicates/Articles/pCreating.html#//apple_ref/doc/uid/TP40001793
强大的谓词,官方文档
https://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/Predicates/Articles/pCreating.html#//apple_ref/doc/uid/TP40001793