Preference keys in iOS Swift - Cheat Sheet & Quick Revision

Recall & Review

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What is a UserDefaults key in iOS Swift development?

A UserDefaults key is a unique identifier used to store and retrieve user settings or preferences in UserDefaults. It helps keep data organized and accessible.

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How do you define a UserDefaults key for a Boolean value in Swift?

You create a constant string key, for example: <code>let darkModeKey = "darkModeEnabled"</code>, then use it to save or read a Boolean from UserDefaults.

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Why should you use constants for UserDefaults keys instead of hardcoding strings everywhere?

Using constants avoids typos, makes code easier to maintain, and ensures consistency when accessing stored preferences.

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How do you save a value using a UserDefaults key in UserDefaults?

Use UserDefaults.standard.set(value, forKey: key), where key is your UserDefaults key.

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How do you read a value using a UserDefaults key from UserDefaults?

Use UserDefaults.standard.bool(forKey: key) for Booleans or UserDefaults.standard.string(forKey: key) for strings, replacing key with your UserDefaults key.

What is the main purpose of a UserDefaults key in iOS development?

A To handle animations

B To create UI elements

C To manage network requests

D To uniquely identify stored user settings

UserDefaults keys uniquely identify user settings stored in UserDefaults.

Which class is commonly used to save and retrieve preferences using keys?

A UserDefaults

B UIViewController

C NotificationCenter

D FileManager

UserDefaults is the class used to store and retrieve user preferences with keys.

Why is it better to use a constant for a UserDefaults key instead of a string literal?

A To make the app run faster

B To avoid typos and keep code consistent

C To reduce app size

D To improve UI design

Constants prevent typos and help maintain consistent keys throughout the code.

How do you save a Boolean value to UserDefaults with a key?

A UserDefaults.standard.save(true, "key")

B UserDefaults.standard.get(true, forKey: "key")

C UserDefaults.standard.set(true, forKey: "key")

D UserDefaults.standard.store(true, "key")

The correct method to save is set(_:forKey:).

Which method reads a Boolean value from UserDefaults?

A UserDefaults.standard.bool(forKey: "key")

B UserDefaults.standard.getBool("key")

C UserDefaults.standard.readBool("key")

D UserDefaults.standard.fetchBool("key")

The method bool(forKey:) reads a Boolean value from UserDefaults.

Explain what a UserDefaults key is and how it is used in iOS Swift development.

Think about how apps remember user choices.

Describe the steps to save and read a Boolean preference using a UserDefaults key in Swift.

Focus on the methods used with UserDefaults.