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I have been attempting to debug this for over 10 hours...
I am working on implementing Apple's MobileNetV2 CoreML model into a Swift Playgrounds. I performed the following steps
Compiled CoreML model in regular Xcode project
Moved Compiled CoreML (MobileNetV2.mlmodelc) model to Resources folder of Swift Playground
Copy Paste the model class (MobileNetV2.swift) into the Sources folder of Swift Playground
Use UIImage extensions to resize and convert UIImage into CVbuffer
Implement basic code to run the model.
However, every time I run this, it keeps giving me this error:
MobileNetV2.swift:100: Fatal error: Unexpectedly found nil while unwrapping an Optional value
From the automatically generated model class function:
/// URL of model assuming it was installed in the same bundle as this class
class var urlOfModelInThisBundle : URL {
let bundle = Bundle(for: self)
return bundle.url(forResource: "MobileNetV2", withExtension:"mlmodelc")!
}
The model builds perfectly, this is my contentView Code:
import SwiftUI
struct ContentView: View {
func test() -> String{
// 1. Load the image from the 'Resources' folder.
let newImage = UIImage(named: "img")
// 2. Resize the image to the required input dimension of the Core ML model
// Method from UIImage+Extension.swift
let newSize = CGSize(width: 224, height: 224)
guard let resizedImage = newImage?.resizeImageTo(size: newSize) else {
fatalError("⚠️ The image could not be found or resized.")
}
// 3. Convert the resized image to CVPixelBuffer as it is the required input
// type of the Core ML model. Method from UIImage+Extension.swift
guard let convertedImage = resizedImage.convertToBuffer() else {
fatalError("⚠️ The image could not be converted to CVPixelBugger")
}
// 1. Create the ML model instance from the model class in the 'Sources' folder
let mlModel = MobileNetV2()
// 2. Get the prediction output
guard let prediction = try? mlModel.prediction(image: convertedImage) else {
fatalError("⚠️ The model could not return a prediction")
}
// 3. Checking the results of the prediction
let mostLikelyImageCategory = prediction.classLabel
let probabilityOfEachCategory = prediction.classLabelProbs
var highestProbability: Double {
let probabilty = probabilityOfEachCategory[mostLikelyImageCategory] ?? 0.0
let roundedProbability = (probabilty * 100).rounded(.toNearestOrEven)
return roundedProbability
}
return("\(mostLikelyImageCategory): \(highestProbability)%")
}
var body: some View {
VStack {
let _ = print(test())
Image(systemName: "globe")
.imageScale(.large)
.foregroundColor(.accentColor)
Text("Hello, world!")
Image(uiImage: UIImage(named: "img")!)
}
}
}
Upon printing my bundle contents, I get these:
["_CodeSignature", "metadata.json", "__PlaceholderAppIcon76x76@2x~ipad.png", "Info.plist", "__PlaceholderAppIcon60x60@2x.png", "coremldata.bin", "{App Name}", "PkgInfo", "Assets.car", "embedded.mobileprovision"]
Anything would help 🙏
For additional reference, here are my UIImage extensions in ExtImage.swift:
//Huge thanks to @mprecke on github for these UIImage extension function.
import Foundation
import UIKit
extension UIImage {
func resizeImageTo(size: CGSize) -> UIImage? {
UIGraphicsBeginImageContextWithOptions(size, false, 0.0)
self.draw(in: CGRect(origin: CGPoint.zero, size: size))
let resizedImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return resizedImage
}
func convertToBuffer() -> CVPixelBuffer? {
let attributes = [
kCVPixelBufferCGImageCompatibilityKey: kCFBooleanTrue,
kCVPixelBufferCGBitmapContextCompatibilityKey: kCFBooleanTrue
] as CFDictionary
var pixelBuffer: CVPixelBuffer?
let status = CVPixelBufferCreate(
kCFAllocatorDefault, Int(self.size.width),
Int(self.size.height),
kCVPixelFormatType_32ARGB,
attributes,
&pixelBuffer)
guard (status == kCVReturnSuccess) else {
return nil
}
CVPixelBufferLockBaseAddress(pixelBuffer!, CVPixelBufferLockFlags(rawValue: 0))
let pixelData = CVPixelBufferGetBaseAddress(pixelBuffer!)
let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
let context = CGContext(
data: pixelData,
width: Int(self.size.width),
height: Int(self.size.height),
bitsPerComponent: 8,
bytesPerRow: CVPixelBufferGetBytesPerRow(pixelBuffer!),
space: rgbColorSpace,
bitmapInfo: CGImageAlphaInfo.noneSkipFirst.rawValue)
context?.translateBy(x: 0, y: self.size.height)
context?.scaleBy(x: 1.0, y: -1.0)
UIGraphicsPushContext(context!)
self.draw(in: CGRect(x: 0, y: 0, width: self.size.width, height: self.size.height))
UIGraphicsPopContext()
CVPixelBufferUnlockBaseAddress(pixelBuffer!, CVPixelBufferLockFlags(rawValue: 0))
return pixelBuffer
}
}
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