14.swift-可选类型应用场景

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

import UIKit
//可选类型的应用场景


//通过一个字符创建一个NSURL对象
let url : NSURL? = NSURL.init(string: "http://www.youguo.com");

//根据url创建NSURLRequest对象
if let url = url {
    let request = NSURLRequest.init(url: url as URL);
    print(request);
}