Error handling and crash reporting

Section 5.4: Error Handling and Crash Reporting

In this section, we'll tackle the inevitable reality of software development: errors and crashes. You'll learn how to anticipate, handle, and gracefully recover from errors, as well as how to gather valuable crash reports to diagnose and fix issues in your apps.

Types of Errors:

Compile-Time Errors: Detected by the compiler during code analysis (e.g., syntax errors, type mismatches).

Runtime Errors: Occur during app execution (e.g., invalid array access, division by zero).

Logical Errors: Flaws in your program's logic that lead to incorrect behavior.

Error Handling in Swift:

Swift provides several mechanisms for handling errors:

Optionals: Used to represent values that may be missing or invalid. Unwrap optionals safely using if let or guard let.

Error Protocol: A standard protocol for representing errors in Swift. You can create custom error types that conform to this protocol.

try, catch, throw: Used for handling and propagating errors in a structured way. The try keyword indicates that a statement might throw an error. The catch block handles the thrown error, and the throw keyword is used to explicitly throw an error.

Example (Error Handling with try, catch, throw):


enum FileError: Error {

    case fileNotFound

    case permissionDenied

    case unknownError


func readFile(atPath path: String) throws -> String {

    guard FileManager.default.fileExists(atPath: path) else {

        throw FileError.fileNotFound



    // ... (code to read file contents)


do {

    let contents = try readFile(atPath: "/path/to/file")

    // ... (use the file contents)

} catch FileError.fileNotFound {

    // Handle file not found error

} catch FileError.permissionDenied {

    // Handle permission denied error

} catch {

    // Handle other errors


Crash Reporting:

When your app crashes in production, crash reports provide crucial information for debugging and fixing the issue.

Crash Reporting Tools:

Xcode Organizer: Xcode's built-in crash reporting tool displays crash reports from users who have opted in to share them with developers.

Third-Party Crash Reporting Services: Services like Firebase Crashlytics, Bugsnag, and Sentry offer more comprehensive crash reporting and analytics features.

Best Practices:

Anticipate Errors: Design your code to handle potential errors gracefully.

Log Errors: Use logging to record error details for analysis.

Recover from Errors: If possible, try to recover from errors and provide a seamless user experience.

Use Crash Reporting: Integrate crash reporting to gather valuable data about crashes in production.

By embracing error handling and crash reporting, you can build more robust and reliable apps that provide a better user experience and help you identify and fix problems quickly.

Course Syllabus