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Explain the role of the `else` block in a guard statement.
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The `else` block in a guard statement contains the code to execute if the guard condition is not met, typically exiting the current scope to prevent further code execution.
Explain how guard statements can handle multiple conditions with an example.
`guard number > 5, number < 10 else { return false }` allows you to check multiple conditions at once, making the validation more concise.
In what scenario would you prefer an if-else statement over a guard statement?
An if-else statement might be preferred if you need to handle multiple branches of logic within both the `if` and `else` sections.
How would you use a guard statement to validate input fields such as username and password in a login form?
Use a guard statement to check if both username and password fields are non-empty: `guard let username = usernameField.text, !username.isEmpty, let password = passwordField.text, !password.isEmpty else { showError(message: 'Both fields are required'); return }`
State a rule about how to write conditions inside a guard statement.
Conditions inside a guard statement must be written in such a way that the code inside the guard’s else block should handle the failure to meet these conditions, ensuring any required exits are performed.
Why should guard statements be used at the start of functions?
Guard statements should be used at the start of functions to quickly handle invalid conditions and exit early, ensuring the function's primary logic is concise and readable.
What should you do if the condition of a guard statement fails?
If the condition of a guard statement fails, you must exit the current scope using `return`, `break`, `continue`, or `throw`.
Provide an example of unwrapping an optional using a guard statement.
`var text: String? = 'Hello World'; guard let unwrappedText = text else { return }; print(unwrappedText)`
Rewrite the following if-else statement using a guard statement: `if number < 5 { return false } return true`.
`guard number > 5 else { return false } return true`
What is the main advantage of using guard statements for input validation?
The main advantage is that it allows for early exits, which makes the function logic clearer and avoids deep nesting.
What is a guard statement in Swift and how is it different from an if-else statement?
A guard statement in Swift ensures conditions are met to proceed with code execution. Unlike an if-else statement, it is used to exit a function, loop, or block early if the condition is not satisfied, improving code readability.
Why is a guard statement preferred over if-let for unwrapping optionals?
Guard is preferred because it improves readability by reducing nesting and placing the early exit condition clearly at the beginning of the block.
Compare the use of guard vs if-let for unwrapping a variable `text: String?`.
Using guard: `guard let unwrappedText = text else { return }` exits the function early if `text` is nil. Using if-let: `if let unwrappedText = text { print(unwrappedText) }` allows for more nesting and less readable flow.
How does using a guard statement improve code readability?
Guard statements provide clear intent and structure, showing the exit conditions early in the function, which makes the code cleaner and more readable, especially for early exits.
How does Swift enforce the rule associated with the guard statement?
Swift enforces the rule by requiring the `else` block in a guard statement to transfer control out of the scope in which it appears (e.g., using `return`, `break`, `continue`, or `throw`).
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