懒加载

//
//  ViewController.swift


import UIKit

class ViewController: UIViewController {

    // 懒加载格式：定义变量时前面使用 lazy 修饰，给变量赋值一个闭包
    // 注意点：1.必须是用var,2.闭包后面必须跟上()
    lazy var dataList:[String] = {
        ()->[String]
        in
        print("创建了")
        return ["jack","lily","zhangsan"]
    }()

    // 如果闭包是用于懒加载可以简化
    lazy var dataList2:[String] = {
        print("创建了2")
        return ["jack","lily","zhangsan"]
    }()

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
        print(dataList2)
        print(dataList2)
        print(dataList2)
    }
}