Swift－单例的使用

1.首先创建一个单例文件，继承NSObject类

import UIKit

class SwiftSingleton: NSObject {

//      单例颜色属性

var color = UIColor.orangeColor()

//这个位置使用static，static修饰的变量会懒加载

internal static let instance = SwiftSingleton()

private override init()

{

print("----");

}

}

2.在控制器里加入一个button

let btn = UIButton(frame:CGRectMake(view.frame.size.width/2-50,100,100,40))

btn.backgroundColor = UIColor.brownColor()

btn.addTarget(self, action: #selector(ViewController.btnClicked), forControlEvents: UIControlEvents.TouchUpInside)

self.view.addSubview(btw)

func btnClicked(){

let sec = SecViewController()

self.navigationController?.pushViewController(sec, animated: true)

}

3.创建第二个控制器

在第二个控制器里创建单例，给单例的属性赋值

self.view.backgroundColor = UIColor.whiteColor()

let R = Float(arc4random()%255)/255.0

let G = Float(arc4random()%255)/255.0

let B = Float(arc4random()%255)/255.0

let color = UIColor.init(colorLiteralRed: R, green: G, blue: B, alpha: 1.0)

//      单例赋值

let single = SwiftSingleton.instance

single.color = color

4.在第一个控制器加入一个方法viewWillAppear

//    单例取值

override func viewWillAppear(animated: Bool) {

super.viewWillAppear(true)

let single = SwiftSingleton.instance

self.view.backgroundColor = single.color

}

实现单例的反向传值