Throwing functions with throws in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a function that can throw an error.

Swift

func checkNumber(_ number: Int) [1] {
    if number < 0 {
        throw NSError(domain: "Negative number", code: 1)
    }
}

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

Athrow

Bthrows

Ctry

Dcatch

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'throw' instead of 'throws' in the function declaration.

Confusing 'try' with the function declaration keyword.

The keyword throws is used to declare that a function can throw an error.

2fill in blank

medium

Complete the code to call a throwing function using the correct keyword.

Swift

do {
    try [1](5)
} catch {
    print("Error occurred")
}

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

Athrow

Bthrows

CcheckNumber

Dcatch

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'throws' or 'throw' instead of the function name.

Omitting the 'try' keyword before the function call.

When calling a throwing function, you use the try keyword followed by the function name.

3fill in blank

hard

Fix the error in the function declaration to properly indicate it can throw errors.

Swift

func validateAge(_ age: Int) [1] {
    if age < 18 {
        throw NSError(domain: "Too young", code: 2)
    }
}

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

Athrow

Bcatch

Ctry

Dthrows

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'throw' instead of 'throws' in the function declaration.

Confusing 'try' with the declaration keyword.

The function declaration must use throws to indicate it can throw errors, not throw.

4fill in blank

hard

Fill both blanks to create a throwing function and call it correctly.

Swift

func [1](_ value: Int) [2] {
    if value == 0 {
        throw NSError(domain: "Zero value", code: 3)
    }
}

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

Athrows

BcheckValue

Cthrow

Dtry

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the function name and 'throws' keyword.

Using 'throw' instead of 'throws'.

The function name is checkValue and it must be declared with throws to indicate it can throw errors.

5fill in blank

hard

Fill all three blanks to declare a throwing function, call it with try, and handle errors.

Swift

func [1](_ input: String) [2] {
    if input.isEmpty {
        throw NSError(domain: "Empty input", code: 4)
    }
}

do {
    [3] [1]("")
} catch {
    print("Caught an error")
}

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

AprocessInput

Bthrows

Ctry

Dthrow

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'throw' instead of 'throws' in the declaration.

Omitting 'try' when calling the function.

The function name is processInput, declared with throws. When calling it, use try to handle possible errors.