I am converting my app from Objective-C to Swift and I am having a problem unarchiving (in Swift) my persist objects that were previously archived in Objective-C. For example, I have an NSMutableDictionary file that was archived with the following Objective-C code: NSString *indexFilename = "somefilename"; NSMutableDictionary *index = [NSMutableDictionary dictionary]; // Dictionary gets populated... // Save it... [NSKeyedArchiver archiveRootObject:index toFile:indexFilename];These files are unarchived just fine in the Objective-C version of the app with: NSMutableDictionary *index = nil; if ([[NSFileManager defaultManager] fileExistsAtPath:indexFilename]) { index = [NSKeyedUnarchiver unarchiveObjectWithFile:indexFilename]; }But in the new Swift version, the following code sets index to nil: let filename = "somefilename" var index = NSKeyedUnarchiver.unarchiveObjectWithFile(filename)Should this just work or is there something else I need to do to unarchive these files successfully in Swift?Thanks.