Flashcards for:
CS50 iOS Track 4: iOS Photo Filter App - Lecture Notes

Ensure the app handles the original image state properly and use optional unwrapping safely with guard let or if let to prevent crashes.

Create an IBAction for the 'Choose Photo' button, configure it to present the UIImagePickerController, and connect the button to this action in the storyboard.

Embed a Navigation Controller by selecting the initial ViewController and choosing 'Embed In' -> 'Navigation Controller' from the menu, then set the title of the navigation bar.

Add a title bar with a button to select a photo, an ImageView to display selected images, and buttons to apply filters to the image.

Aspect Fit scales the image to fit within the ImageView bounds while maintaining the image's aspect ratio, ensuring the image is not distorted.

Open Xcode, create a new single view app project, name it 'Fiftygram', and set the language to Swift.

IBAction and IBOutlet are used to connect UI components to code. IBAction methods handle button taps, while IBOutlet properties reference UI components like ImageView.

First, create an action method (e.g., applySepia). Use CIFilter to create a sepia filter, apply it to a CIImage converted from the selected UIImage, and display the filtered image by updating the ImageView.

CIFilter is used to create and apply various image filters. It processes CIImage instances to generate filtered images (e.g., sepia, noir) that are then displayed in the app's ImageView.

Use UIImagePickerController to select a photo, handle the selected photo in imagePickerController(didFinishPickingMediaWithInfo:), and update the ImageView with the selected UIImage.

Additional filters include Noir and Vintage. Each filter can be implemented by adding corresponding buttons, creating IBActions (e.g., applyNoir, applyVintage), and using appropriate CIFilter instances to process the selected image.

Create UIImagePickerController, set picker.delegate = self, conform to UIImagePickerControllerDelegate and UINavigationControllerDelegate, present the photo library using navigationController.present(picker, animated: true, completion: nil), and handle photo selection with imagePickerController(didFinishPickingMediaWithInfo:).

Using guard let or if let ensures safe unwrapping of optionals, preventing crashes due to nil values when converting or updating the image.

After selecting a photo, implement imagePickerController(didFinishPickingMediaWithInfo:) method to get the selected image, display it in the ImageView, and manually dismiss the picker using navigationController.dismiss(animated: true, completion: nil).

Conforming to these protocols allows the class to manage the photo selection process and handle the events triggered by UIImagePickerController, such as photo selection and picker dismissal.