Mark! In case you're still wondering how to do this, I just got it working by using [openPanelObj setDirectoryURL: [NSURL fileURLWithPath: NSS(woof)]], where woof is the filename concatenated to the directory path and NSS is a #define that makes an NSString from a C string. It was a problem for me for 13 years until I reread Michael Robinson's answer here: How can I have a default file selected for opening in an NSOpenPanel?