[移动开发]IOS swift项目的单例模式.swift5以后的单例模式

IOS swift项目的单例模式.swift5以后的单例模式

不能继承NSObject
第一种写法，最简单

class SoundTools{
    static let sharedInstance = SoundTools()
    private init() { }

第2种写法

class SoundTools{
    //提供全局访问点
    class var sharedInstance2: SoundTools {
        struct Static {
            static let inst: SoundTools = SoundTools()
        }
        return Static.inst
    }
 }

在打印地方，写一个打印地址的函数,否则print函数无法打印地址

func address<T: AnyObject>(o: T) -> String {
        return String.init(format: "%018p", unsafeBitCast(o, to: Int.self))
    }

 override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
//        print(SoundTools.sharedInstance)
        print(address(o: SoundTools.sharedInstance)) 
//        print(SoundTools.sharedInstance2)
        print(address(o: SoundTools.sharedInstance2))
        print(address(o: Peson()))
        print("===")
    }

看看控制台输出

0x00006000016f0f20
0x00006000016ec170
0x00006000016ec180
===
0x00006000016f0f20
0x00006000016ec170
0x00006000016f0eb0
===

证明单例没有问题