class MyClass {
  deinit{
    print("MyClass deinit")
  }
}
var cls1:MyClass? = MyClass()
var cls2:MyClass? = cls1
var cls3:MyClass? = cls2
cls2 = nil
cls1 = nil
//执行下面代码后才会打印“MyClass deinit”
cls3 = nil

class MyClassOne {
  var cls:MyClassTwo?
  deinit{
    print("ClassOne deinit")
  }
}
class MyClassTwo {
  var cls:MyClassOne?
  deinit{
    print("ClassTwo deinit")
  }
}
var obj1:MyClassOne? = MyClassOne()
var obj2:MyClassTwo? = MyClassTwo()
obj1?.cls = obj2
obj2?.cls = obj1
obj1=nil
obj2=nil
//没有打印析构函数的调用信息

//关于弱引用的演示
class MyClassThree{
  weak var cls:MyClassFour?
  deinit{
    print("ClassThree deinit")
  }
}
class MyClassFour {
  var cls:MyClassThree?
  deinit{
    print("ClassFour deinit")
  }
}
var obj3:MyClassThree? = MyClassThree()
var obj4:MyClassFour? = MyClassFour()
obj3?.cls = obj4
obj4?.cls = obj3
obj4=nil
//此时obj3中的cls也为nil
obj3?.cls

class MyClassFive{
  var cls:MyClassSix
  init(param:MyClassSix){
    cls = param
  }
  deinit{
    print("ClassFive deinit")
  }
}
class MyClassSix{
  var cls:MyClassFive?
  deinit{
    print("ClassSix deinit")
  }
}
var obj6:MyClassSix? = MyClassSix()
var obj5:MyClassFive? = MyClassFive(param: obj6!)
obj6?.cls = obj5
obj5=nil
obj6=nil
//没有打印任何信息

class MyClassFive{
  unowned var cls:MyClassSix
  init(param:MyClassSix){
    cls = param
  }
  deinit{
    print("ClassFive deinit")
  }
}
class MyClassSix{
  var cls:MyClassFive?
  deinit{
    print("ClassSix deinit")
  }
}
var obj6:MyClassSix? = MyClassSix()
var obj5:MyClassFive? = MyClassFive(param: obj6!)
obj6?.cls = obj5
obj5=nil
obj6=nil

class MyClassFive{
  unowned var cls:MyClassSix
  init(param:MyClassSix){
    cls = param
  }
  deinit{
    print("ClassFive deinit")
  }
}
class MyClassSix{
  var cls:MyClassFive?
  deinit{
    print("ClassSix deinit")
  }
}
var obj6:MyClassSix? = MyClassSix()
var obj5:MyClassFive? = MyClassFive(param: obj6!)
obj6?.cls = obj5
obj6=nil
obj5?.cls

class MyClassSeven{
  unowned var cls:MyClassEight
  init(param:MyClassEight){
    cls = param
  }
  deinit{
    print("ClassSeven deinit")
  }
}
class MyClassEight{
  var cls:MyClassSeven!
  init(){
    cls = MyClassSeven(param:self)
  }
  deinit{
    print("ClassEight deinit")
  }
}
var obj7:MyClassEight? = MyClassEight()
obj7=nil

class MyClassNine {
  var name:String = "HS"
  lazy var closure:()->Void = {
    //闭包中使用引用值会使引用+1
    print(self.name)
  }
  deinit{
    print("ClassNine deinit")
  }
}
var obj9:MyClassNine? = MyClassNine()
obj9?.closure()
obj9=nil
//不会打印析构信息

class MyClassNine {
  var name:String = "HS"
  lazy var closure:()->Void = {
    [unowned self]()->Void in
    print(self.name)
  }
  deinit{
    print("ClassNine deinit")
  }
}
var obj9:MyClassNine? = MyClassNine()
obj9?.closure()
obj9=nil