ErrorHandlingPlayground.swift

import UIKit


// Step 2 create enum for custom error
enum CustomError: Error {
    case invalidUrl
    case emptyUrl
    case other
}

// Step 1. function with throws keyword
func validateUrl(urlString: String) throws -> Bool {
    guard !urlString.isEmpty else {
        throw CustomError.emptyUrl
    }
    
    guard URL(string: urlString) != nil else {
        throw CustomError.invalidUrl
    }
    
    return true
}


// Step 3 call the function with do try catch
let urlString = ""
do {
    let result = try validateUrl(urlString: urlString)
    
    // Step 5 continue the process if it success
    print("is url valid? \(result)")
}
catch {
    // Step 4 show error to users
    print("error \(error)")
}