Preference keys in iOS Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to save a string value to UserDefaults using the key "username".

iOS Swift

UserDefaults.standard.set("John", forKey: [1])

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

A"username"

B"user_name"

C"user"

D"name"

Attempts:

3 left

💡 Hint

Common Mistakes

Using a key with underscores instead of the exact key.

Forgetting to put the key in quotes.

The key must exactly match "username" to store the value correctly.

2fill in blank

medium

Complete the code to retrieve a boolean preference with key "isDarkMode" from UserDefaults.

iOS Swift

let darkModeEnabled = UserDefaults.standard.[1]("isDarkMode")

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

Ainteger(forKey:)

Bbool(forKey:)

Cstring(forKey:)

Ddouble(forKey:)

Attempts:

3 left

💡 Hint

Common Mistakes

Using string(forKey:) when expecting a boolean.

Using integer(forKey:) or double(forKey:) incorrectly.

Use bool(forKey:) to get a boolean value from UserDefaults.

3fill in blank

hard

Fix the error in the code to remove a preference with key "userAge" from UserDefaults.

iOS Swift

UserDefaults.standard.[1](forKey: "userAge")

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

AremoveObject

BdeleteObject

CclearObject

DunsetObject

Attempts:

3 left

💡 Hint

Common Mistakes

Using deleteObject or clearObject which do not exist.

Using set(nil, forKey:) which is not recommended.

The correct method to remove a value is removeObject(forKey:).

4fill in blank

hard

Fill both blanks to save an integer preference "launchCount" incremented by 1.

iOS Swift

let count = UserDefaults.standard.[1]("launchCount")
UserDefaults.standard.set(count [2] 1, forKey: "launchCount")

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

Ainteger(forKey:)

B+

C-

Ddouble(forKey:)

Attempts:

3 left

💡 Hint

Common Mistakes

Using double(forKey:) instead of integer(forKey:).

Using - instead of + to increment.

Retrieve the integer value with integer(forKey:) and add 1 to increment.

5fill in blank

hard

Fill all three blanks to create a dictionary preference with keys "theme", "fontSize", and "notifications".

iOS Swift

let settings: [String: Any] = ["theme": [1], "fontSize": [2], "notifications": [3]]
UserDefaults.standard.set(settings, forKey: "userSettings")

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

A"dark"

B14

Ctrue

D"light"

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes incorrectly around numbers or booleans.

Mixing up the order of values.

The theme is a string "dark", fontSize is integer 14, notifications is boolean true.