Why error handling is explicit in Swift - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

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

Swift

func readFile() [1] { }

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

Athrows

Bthrow

Ctry

Dcatch

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'throw' instead of 'throws' to declare the function.

Confusing 'try' with the function declaration keyword.

The throws keyword declares that the function can throw an error.

2fill in blank

medium

Complete the code to call a throwing function with error handling.

Swift

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

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Atry

Bthrow

Cthrows

Dcatch

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'throws' instead of 'catch' after the do block.

Placing 'try' outside the do block.

The catch block handles errors thrown by the try call.

3fill in blank

hard

Fix the error in the code to correctly handle errors when calling a throwing function.

Swift

let result = [1] readFile()

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AreadFile()

Bthrows

Ctry

Dcatch

Attempts:

3 left

💡 Hint

Common Mistakes

Calling the function without 'try' causes a compile error.

Using 'throws' instead of 'try' when calling the function.

The try keyword is required before calling a function that can throw an error.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that filters keys with values greater than 10.

Swift

let filtered = dictionary.filter { $0.value [1] 10 }.map { ($0.key, $0.value) }.reduce(into: [:]) { $0[$1.[2]] = $1.1 }

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A>

B<

Ckey

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' in the filter condition.

Using 'value' instead of 'key' when accessing dictionary keys.

The filter uses > to select values greater than 10, and key extracts the dictionary key.

5fill in blank

hard

Fill all three blanks to create a throwing function that reads a file and returns its content length if successful.

Swift

func readFile() [1] -> Int {{
    let content = try String(contentsOfFile: "file.txt")
    return content.[2]
}}

let length = try? readFile() [3] nil

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

Athrows

Bcount

C??

Dtry

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting 'throws' in the function declaration.

Using 'length' instead of 'count' for string length.

Not using '??' to handle the optional result.

The function declares throws, returns the count of the content string, and uses ?? to provide a default value if the call fails.