How to Handle Errors in Swift?

Error handling in Swift helps you deal with unexpected issues like network problems, bad input, or file read errors without crashing your app. Swift gives you a clean way to manage these situations using do-try-catch, so you can throw errors when something goes wrong and catch them in one place to handle them properly.

Error Handling Workflow

• Define an Error type (usually an enum conforming to the Error protocol)
• Use throw to raise an error
• Use try to call a throwing function
• Use do-catch to handle the error

Step-by-Step Breakdown of Error Handling in Swift with an Example

Define an Error Type

enum FileError: Error { case fileNotFound case unreadable case encodingFailed
}

Throw an Error in a Function

func readFile(name: String) throws -> String { guard name == "data.txt" else { throw FileError.fileNotFound } return "File content"
}

Handle the Error with do-try-catch

do { let content = try readFile(name: "wrong.txt") print(content)
} catch FileError.fileNotFound { print("⚠️ File not found.")
} catch { print("⚠️ An unknown error occurred: \(error)")
}

Choosing the Right try Approach in Swift

let result = try? readFile(name: "data.txt") // Optional("File content")
let force = try! readFile(name: "data.txt") // Unsafe if error is thrown

Custom Error Messages

You can conform your error enum to LocalizedError or CustomStringConvertible to provide better messages:

extension FileError: LocalizedError { var errorDescription: String? { switch self { case .fileNotFound: return "The file could not be found." case .unreadable: return "The file is unreadable." case .encodingFailed: return "The file could not be encoded." } }
}

Conclusion

Error handling in Swift lets you manage issues like network errors or bad input without crashing the app. When you hire Swift developers who use do-try-catch well, your app becomes more stable and reliable.