Affectiva detecting emotion from file macOS

Question

I'm trying to make a macOS app that detects emotions from picture using files from a drive. I have a problem with adding path in correct way to "usingFile". Currently Xcode shows error: "Use of undeclared identifier 'path' ".

- (void)viewDidLoad {
    [super viewDidLoad];

// detector
self.detector = [[AFDXDetector alloc] initWithDelegate: self
                                             usingFile: (NSString *)path
                                          maximumFaces: (NSUInteger)maximumFaces;

[self.detector setDetectAllEmotions:YES];
self.detector.maxProcessRate = 5;
[self.detector start];
}

Documentation for Affdex-SDK: http://affectiva.github.io/developerportal/pages/platforms/v4_0_0/ios/classdocs/interface_a_f_d_x_detector.html