FailableAndThrowingInit.swift

//: Playground - noun: a place where people can play

import UIKit

//initialization
//value types get defautlt initializers , structs and enums

//1- failable and throwing initializers

//What happens if we can't initialize an object? This is a common occurrence if initialization depends on external data. Swift gives us two ways to deal with this - failable and throwing initializers.

//FAILABLE INITIALIZER

//if there is no data return nil
class Person {
    let name: String
    let age: Int
    
    init?(dict:[String : AnyObject]) {
        
        guard let name = dict["name"] as? String, let age = dict["age"] as? Int else {
            return nil
        }
        self.name = name
        self.age = age
    }
}

//THROWING INITIALIZER
//throwing initializers returns an error on initialization instead of returning nil

//a simple enum for an error case
enum HumanError: Error {
    case invalidData
}

class Human {
    let name: String
    let age: Int
    
    init(dict:[String : AnyObject]) throws {
        
        guard let name = dict["name"] as? String, let age = dict["age"] as? Int else {
          throw HumanError.invalidData
        }
        self.name = name
        self.age = age
    }
}