I'm trying to update a class variable (prediction) and then use that variable as data for a segue (AnalyzeSegue). However even if I update the class variable within the function (detectScene), the class variable is a nil value during prepare for segue causing my app to crash.
Most of the code was via this tutorial (just customized for my model):
https://www.raywenderlich.com/577-core-ml-and-vision-machine-learning-in-ios-11-tutorial
class PreviewViewController: UIViewController {
var prediction: String?
@IBOutlet weak var Photo: UIImageView!
//This button is what starts the segue into the next screen(
@IBAction func analyze(_ sender: Any) {}
override func prepare(for segue: UIStoryboardSegue, sender: Any?){
if segue.identifier == "saveSegue"{
"save photo"}
else if segue.identifier == "AnalyzeSegue" #Analyze button
{
let AnalyzeVC = segue.destination as! AnalyzeViewController
let ciImage = CIImage(image:Photo.image!)
self.detectScene(image: ciImage!)
print(self.prediction!) #nil value
if let hasPrediction = self.prediction {
AnalyzeVC.predictionLabel.text = hasPrediction
AnalyzeVC.imagePreview.image = Photo.image}
}
detect function:
extension PreviewViewController{
func detectScene(image: CIImage) {
var localPrediction: String?
// Load the ML model through its generated class
guard let model = try? VNCoreMLModel(for: test2().model)
else {
fatalError("can't load Places ML model")
}
let request = VNCoreMLRequest(model: model) { [weak self] request, error in
guard let results = request.results as? [VNCoreMLFeatureValueObservation]
else {
fatalError("unexpected result type from VNCoreMLRequest")
}
let topResult = results.first?.featureValue.multiArrayValue
DispatchQueue.main.async { () in
var max_value : Float32 = 0
for i in 0..<topResult!.count{
if max_value < topResult![i].floatValue{
max_value = topResult![i].floatValue
localPrediction = String(i)
}
} //#end of loop
self?.prediction = localPrediction #update self?.prediction
print(self?.prediction, "Inside Function") #seems to have value
} //#end of dispatch Queue
} //#end of closure
let handler = VNImageRequestHandler(ciImage: image)
DispatchQueue.global(qos: .userInteractive).async {
do {
try handler.perform([request])
} catch {print(error)}
}
} //end of function
} //end of extension
So the detectScene function is supposed to update the class variable prediction and the that info is used in the prepare for seugue function.
The function seems to be update the value, as I have a print statement within the function was printing out an optional value:
print(self?.prediction, "Inside Function")
Thank you for your help.
