Swift - 单例

private let shareInstanceTest = testShareInstance()

class testShareInstance {
    
    var age:Int = 0
    
    class var shareInstance : testShareInstance {
        
        return shareInstanceTest
    }
    
}

        let share1 = testShareInstance.shareInstance
        share1.age = 20
        let share2 = testShareInstance.shareInstance
        share2.age = 30
        print(share1.age) // 30
        print(share2.age) // 30