- [NSWorkspace iconForFile：] http://developer.apple.com/library/mac/documentation/Cocoa/Reference/ApplicationKit/Classes/NSWorkspace_Class/Reference/Reference.html#//apple_ref/doc/uid/20000391-iconForFileType_\"> - [NSWorkspace iconForFileType：] 。你试过了吗？

Underneath -[NSWorkspace iconForFile:] in the documentation is -[NSWorkspace iconForFileType:]. Have you tried that?