NSWorkSpace import

I call this line in my app:

[[NSWorkspace sharedWo开发者_运维问答rkspace] openFile:[LogUtilisateur singletonLogUtilisateur].cheminFichier withApplication:@"Mail"];

but when I compile, xcode said: NSWorkSpace undeclared.

There is a import or a special framework I must include to work with NSWorkSpace?

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This class belongs to AppKit framework. But it is available only for MacOS