ImagePicker

Using UIImagePickerController.

Set your class as the delegate for UIImagePickerController

imagePickerController.delegate = self 

UIImagePickerDelegate methods

extension ImagesViewController: UIImagePickerControllerDelegate, UINavigationControllerDelegate {
  func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
    dismiss(animated: true)
  }
  
  func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
    guard let image = info[UIImagePickerController.InfoKey.originalImage] as? UIImage else {
      return
    }
    selectedImage = image
    dismiss(animated: true)
  }
}

Checking if the camera is available

if UIImagePickerController.isSourceTypeAvailable(.camera) {
  alertController.addAction(cameraAction)
}

info.list key needed to access the camera

If the NSCameraUsageDescription is not added in the info.plist the following crash will occur.

This app has crashed because it attempted to access privacy-sensitive data without a usage description. The app's Info.plist must contain an NSCameraUsageDescription key with a string value explaining to the user how the app uses this data.

Resizing a UIImage to reduce the in app memory size

extension UIImage {
  func resizeImage(to width: CGFloat, height: CGFloat) -> UIImage {
    let size = CGSize(width: width, height: height)
    let renderer = UIGraphicsImageRenderer(size: size)
    return renderer.image { (context) in
      self.draw(in: CGRect(origin: .zero, size: size))
    }
  }
}

Keeping the aspect ratio of a UIImage

import AVFoundation

let rect = AVMakeRect(aspectRatio: image.size, insideRect: UIScreen.main.bounds)

Converting a UIImage object to Data for persisting to disk

let imageData = resizedImage.jpegData(compressionQuality: 1.0)

Useful to create an identifier for custom objects

Comes in very handy when conforming your object to hashable for uniqueness.

struct ImageObject: Codable {
  let imageData: Data
  let date: Date
  let identifier = UUID().uuidString
}

Present an action sheet via UIAlertController

private func showDeleteAlert(forCell indexPath: IndexPath) {
  let alertController = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
  let cancelAction = UIAlertAction(title: "Cancel", style: .cancel)
  let deleteAction = UIAlertAction(title: "Delete", style: .destructive) { [weak self] alertAction in
    self?.deleteImageObject(indexPath: indexPath)
  }
  alertController.addAction(cancelAction)
  alertController.addAction(deleteAction)
  present(alertController, animated: true)
}

Adding a long press gesture to a view

private lazy var longPressGesture: UILongPressGestureRecognizer = {
  let gesture = UILongPressGestureRecognizer()
  gesture.addTarget(self, action: #selector(longPress(gesture:)))
  return gesture
}()

addGestureRecognizer(longPressGesture)

@objc
private func longPress(gesture: UILongPressGestureRecognizer) {
  if gesture.state == .began {
    gesture.state = .cancelled
    return
  }
  delegate?.didLongPressOnCell(self)
}