数据格式化https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/DataFormatting/DataFormatting.html#//apple_ref/doc/uid/10000029-CJBCGJCJ 统一类型标识符https://developer.apple.com/library/archive/documentation/Miscellaneous/Reference/UTIRef/Articles/System-DeclaredUniformTypeIdentifiers.html
