Camera and photo library in iOS Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the framework needed to access the photo library.

iOS Swift

import UIKit
import [1]

Drag options to blanks, or click blank then click option'

AMapKit

BPhotosUI

CCoreData

DAVFoundation

Attempts:

3 left

💡 Hint

Common Mistakes

Importing unrelated frameworks like CoreData or MapKit.

Forgetting to import PhotosUI when working with photo library.

The PhotosUI framework is used to access the photo library and camera features in iOS apps.

2fill in blank

medium

Complete the code to declare a UIImagePickerController variable.

iOS Swift

class ViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
  var imagePicker = [1]()
}

Drag options to blanks, or click blank then click option'

AUIImage

BUIImageView

CUIViewController

DUIImagePickerController

Attempts:

3 left

💡 Hint

Common Mistakes

Using UIImageView instead of UIImagePickerController.

Confusing UIViewController with UIImagePickerController.

The UIImagePickerController is the class used to present the camera or photo library interface.

3fill in blank

hard

Fix the error in the code to present the image picker for the photo library.

iOS Swift

func openPhotoLibrary() {
  imagePicker.sourceType = [1]
  present(imagePicker, animated: true)
}

Drag options to blanks, or click blank then click option'

AUIImagePickerController.SourceType.photoLibrary

BUIImagePickerController.SourceType.camera

CUIImagePickerController.SourceType.savedPhotosAlbum

DUIImagePickerController.SourceType.photoAlbum

Attempts:

3 left

💡 Hint

Common Mistakes

Using camera source type when wanting the photo library.

Using a non-existent source type like photoAlbum.

To open the photo library, set sourceType to photoLibrary.

4fill in blank

hard

Fill both blanks to check if the camera is available and set the source type accordingly.

iOS Swift

if UIImagePickerController.isSourceTypeAvailable([1]) {
  imagePicker.sourceType = [2]
}

Drag options to blanks, or click blank then click option'

AUIImagePickerController.SourceType.camera

BUIImagePickerController.SourceType.photoLibrary

CUIImagePickerController.SourceType.savedPhotosAlbum

DUIImagePickerController.SourceType.cameraRoll

Attempts:

3 left

💡 Hint

Common Mistakes

Checking for photoLibrary availability but setting camera source type.

Using non-existent source types like cameraRoll.

First, check if the camera is available, then set the source type to camera.

5fill in blank

hard

Fill all three blanks to implement the delegate method that handles the selected image.

iOS Swift

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
  if let selectedImage = info[[1]] as? [2] {
    imageView.image = selectedImage
  }
  picker.[3](animated: true, completion: nil)
}

Drag options to blanks, or click blank then click option'

AUIImagePickerController.InfoKey.originalImage

BUIImagePickerController.InfoKey.editedImage

CUIImage

Ddismiss

Attempts:

3 left

💡 Hint

Common Mistakes

Using editedImage key when originalImage is expected.

Not casting the image to UIImage.

Forgetting to dismiss the picker.

The delegate method uses InfoKey.originalImage to get the selected image as a UIImage, then dismisses the picker.

Practice

1. What is the purpose of setting sourceType to .camera in UIImagePickerController?

easy

A. To select an existing photo from the photo library

B. To record a video using the device camera

C. To allow the user to take a new photo using the device camera

D. To open the device settings

Solution

1. Step 1: Understand sourceType usage

   The sourceType property of UIImagePickerController defines where the image will come from.

2. Step 2: Identify the effect of .camera

   Setting sourceType to .camera opens the device camera to take a new photo.

3. Final Answer:

   To allow the user to take a new photo using the device camera -> Option C

4. Quick Check:

   sourceType = .camera means take new photo [OK]

Hint: Camera sourceType means take a new photo [OK]

Common Mistakes:

• Confusing .camera with .photoLibrary
• Thinking .camera records video by default
• Assuming .camera opens settings

2. Which of the following is the correct way to declare a UIImagePickerController and set its delegate in Swift?

easy

A. var picker = UIImagePickerController()
picker.delegate = self()

B. let picker = UIImagePickerController()
picker.delegate = self

C. let picker = UIImagePickerController
picker.delegate = self()

D. var picker = UIImagePickerController
picker.delegate = self

Solution

1. Step 1: Correct initialization syntax

   In Swift, UIImagePickerController() requires parentheses to create an instance.

2. Step 2: Assign delegate properly

   The delegate is assigned as self without parentheses because it is a property, not a function call.

3. Final Answer:

   let picker = UIImagePickerController() picker.delegate = self -> Option B

4. Quick Check:

   Initialize with () and assign delegate without () [OK]

Hint: Use parentheses for init, no parentheses for delegate [OK]

Common Mistakes:

• Forgetting parentheses when creating UIImagePickerController
• Using parentheses when assigning delegate
• Declaring picker without parentheses

3. Given the following code snippet, what will be printed when a user selects a photo from the library?

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
    if let image = info[.originalImage] as? UIImage {
        print("Image selected")
    } else {
        print("No image found")
    }
}

medium

A. Nothing is printed

B. No image found

C. Compilation error

D. Image selected

Solution

1. Step 1: Check the delegate method behavior

   The method imagePickerController(_:didFinishPickingMediaWithInfo:) is called after user picks a photo.

2. Step 2: Understand the info dictionary

   The info dictionary contains the key .originalImage with the selected UIImage if successful.

3. Final Answer:

   Image selected -> Option D

4. Quick Check:

   Image exists in info dictionary after selection [OK]

Hint: If image exists in info, print "Image selected" [OK]

Common Mistakes:

• Assuming image is nil after selection
• Confusing delegate method names
• Not casting info dictionary value properly

4. What is the error in the following Swift code that prevents the image picker from working correctly?

let picker = UIImagePickerController()
picker.sourceType = .camera
picker.delegate = self
present(picker, animated: true)

medium

A. Missing UIImagePickerControllerDelegate and UINavigationControllerDelegate conformance

B. Incorrect sourceType value

C. Delegate should be assigned after presenting picker

D. Cannot present picker without a navigation controller

Solution

1. Step 1: Check delegate conformance requirements

   To use UIImagePickerController delegate methods, the class must conform to UIImagePickerControllerDelegate and UINavigationControllerDelegate.

2. Step 2: Identify missing conformance

   If the class does not conform, delegate methods won't be called and picker won't work properly.

3. Final Answer:

   Missing UIImagePickerControllerDelegate and UINavigationControllerDelegate conformance -> Option A

4. Quick Check:

   Delegate protocols must be adopted for picker to work [OK]

Hint: Always conform to both delegate protocols [OK]

Common Mistakes:

• Forgetting to add delegate protocols to class
• Assigning delegate after presenting picker
• Using wrong sourceType value

5. You want to allow users to either take a new photo or pick one from their library. Which approach correctly handles both options in Swift?

hard

A. Set sourceType dynamically based on user choice, then present a single UIImagePickerController

B. Use sourceType = .savedPhotosAlbum to cover both camera and library

C. Create two UIImagePickerController instances, one with .camera and one with .photoLibrary, and present both simultaneously

D. Use UIImagePickerController only for camera and a custom UI for photo library

Solution

1. Step 1: Understand sourceType flexibility

   A single UIImagePickerController can have its sourceType set to either .camera or .photoLibrary before presenting.

2. Step 2: Handle user choice before presenting picker

   Based on user selection, set the sourceType dynamically and present the picker once.

3. Final Answer:

   Set sourceType dynamically based on user choice, then present a single UIImagePickerController -> Option A

4. Quick Check:

   One picker, sourceType changes per user choice [OK]

Hint: Use one picker, change sourceType before presenting [OK]

Common Mistakes:

• Trying to present two pickers at once
• Using savedPhotosAlbum to cover camera
• Mixing custom UI unnecessarily