Repository pattern in iOS Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a protocol for the repository.

iOS Swift

protocol UserRepository {
    func fetchUser(id: Int) -> [1]
}

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

AInt

BUser?

CString

DVoid

Attempts:

3 left

💡 Hint

Common Mistakes

Returning a String or Int instead of a User object.

Using Void as return type which means no value returned.

The repository protocol should define a method that returns an optional User object when fetching by id.

2fill in blank

medium

Complete the code to implement the repository class conforming to the protocol.

iOS Swift

class UserRepositoryImpl: UserRepository {
    func fetchUser(id: Int) -> [1] {
        // Implementation
        return nil
    }
}

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

AInt

BString

CUser?

DVoid

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different return type than the protocol.

Forgetting to return a value.

The implementation must match the protocol signature, returning an optional User.

3fill in blank

hard

Fix the error in the repository method signature to match the protocol.

iOS Swift

func fetchUser(id: Int) -> [1] {
    // code
}

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

AUser?

BString

CVoid

DUser

Attempts:

3 left

💡 Hint

Common Mistakes

Returning non-optional User which causes mismatch.

Using unrelated types like String or Void.

The method must return an optional User (User?) to match the protocol and handle missing users.

4fill in blank

hard

Fill both blanks to create a repository method that fetches a user by id and returns a default if not found.

iOS Swift

func fetchUserOrDefault(id: Int) -> [1] {
    return fetchUser(id: id) [2] User(name: "Guest")
}

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

AUser

B??

C!

D->

Attempts:

3 left

💡 Hint

Common Mistakes

Using ! which force unwraps and can crash.

Using -> in place of ?? which is invalid.

The method returns a User and uses the nil-coalescing operator ?? to provide a default User if fetchUser returns nil.

5fill in blank

hard

Fill all three blanks to define a repository protocol with a save method and implement it in a class.

iOS Swift

protocol UserRepository {
    func save(user: [1]) -> [2]
}

class UserRepositoryImpl: UserRepository {
    func save(user: [3]) -> Bool {
        // Save logic
        return true
    }
}

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

AUser

BBool

CUser?

DVoid

Attempts:

3 left

💡 Hint

Common Mistakes

Using optional User? as parameter which is not required here.

Returning Void instead of Bool.

Mismatching parameter types between protocol and class.

The protocol defines a save method that takes a User and returns a Bool indicating success. The class implements the same signature.