A Sample code to demonstrate Swift error handling

swift-error-handling.swift

import Foundation

enum PasswordError: Error {
    case TooShort
    case NoNumber
    case CustomMessage(message: String)
}

class PasswordChecker {

    func checkPassword(password: String) throws -> Bool {

        guard password.characters.count >= 8 else {
            throw PasswordError.TooShort
        }

        let numberRegEx  = ".*[0-9]+.*"
        let texttest1 = NSPredicate(format:"SELF MATCHES %@", numberRegEx)
        guard texttest1.evaluate(with: password) == true else {
            throw PasswordError.NoNumber
        }

        guard password.lowercased() != "password" else {
            throw PasswordError.CustomMessage(message: "Common keyword used as a password")
        }

        return true
    }

    func checkMyPassword(password: String) {

        let validatedPasswordStatusWithOptional = try? self.checkPassword(password: password)
        let validatedPasswordStatusWithForce = try! self.checkPassword(password: password)

        do {
            let passwordCheckFlag = try self.checkPassword(password: password)
            print(passwordCheckFlag)
            // Do some amazing things with returned password check flag
        } catch PasswordError.TooShort {
            print("Password is too short")
        } catch PasswordError.NoNumber {
            print("Password must contain at least one number")
        } catch PasswordError.CustomMessage(message: let message) {
            print(message)
        } catch {
            print("Unknown Error Occurred while trying to validate password")
        }
    }
}