On Dec 6, 2009, at 15:58, Mazen M. Abdel-Rahman wrote: > NSNumber * primaryLanguageNumber = [self primaryLanguageID]; > NSString * primaryLanguageString = [primaryLanguageNumber stringValue]; > > primaryLanguageID is of type NSNumber. When I am stepping through the > debugger I can see the variable primaryLanguageNumber being set correctly. > However, once I try to call stringValue on it I get the following error: > > 2009-12-06 16:51:24.525 Averroes[21013:a0f] -[NSCFString stringValue]: > unrecognized selector sent to instance 0x1001d8a70 > > Doesn't that mean that it thinks primaryLanguageNumber is a string? And why > would it see it as a string?
It's seeing it as a string because it *is* a string. That is precisely what the error message is telling you -- that the class of the receiver is NSCFString instead of whatever you intended it to be. There's one fairly obvious scenario that causes this to happen. If you have a text field that modifies the primaryLanguageID property via a binding, and you edit the text field, then the new value will be a NSString regardless of whether the original value was a NSNumber (or anything else). If you want the modified property to be kept as a NSNumber, you must put a numeric formatter on the text field. (Or, if it's part of a table view, then you must put a numeric formatter on the column's text field cell.) (Or, write a setter for the primaryLanguageID property that takes a NSString parameter but stores a NSNumber in the instance variable.) _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
