Error handling (try, catch, throw) in iOS Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to mark the function as throwable.

iOS Swift

func fetchData() [1] {
  // code that might throw an error
}

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Acatch

Bthrows

Cthrow

Dtry

Attempts:

3 left

💡 Hint

Common Mistakes

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

Confusing 'try' with the function declaration.

The throws keyword marks a function that can throw an error.

2fill in blank

medium

Complete the code to call a throwable function correctly.

iOS Swift

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

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AfetchData

BcatchError

CthrowError

DhandleError

Attempts:

3 left

💡 Hint

Common Mistakes

Calling a function without 'try' when it can throw.

Using a wrong function name.

Use try before calling a function that can throw an error, like fetchData().

3fill in blank

hard

Fix the error in the catch block to print the error description.

iOS Swift

do {
  try fetchData()
} catch [1] {
  print(error.localizedDescription)
}

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Alet error

Berror

CcatchError

Dvar error

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting 'let' before error in catch.

Using an undefined variable name.

The catch block must declare the error with let error to access it.

4fill in blank

hard

Fill both blanks to throw a custom error inside the function.

iOS Swift

enum DataError: Error {
  case [1]
}

func fetchData() throws {
  throw DataError.[2]
}

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AnotFound

BinvalidData

Dtimeout

Attempts:

3 left

💡 Hint

Common Mistakes

Using different case names in enum and throw statement.

Forgetting to mark the function as 'throws'.

Define a custom error case notFound and throw it inside the function.

5fill in blank

hard

Fill both blanks to handle a specific error case in catch.

iOS Swift

do {
  try fetchData()
} catch DataError.[1] {
  print("Data not found")
} catch [2] {
  print("Other error: \(error)")
} catch {
  print("Unknown error")
}

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AnotFound

Blet error

Cerror

DDataError

Attempts:

3 left

💡 Hint

Common Mistakes

Not matching the enum case name exactly.

Not declaring the error variable in catch.

Catch the specific notFound error, then catch other errors by declaring let error and printing it.