swift-子类和父类的计算属性同时存在didSet、willS

子类和父类的计算属性同时存在didSet、willSet时，调用顺序探索

class GitArtOS {
    var content: String = "我是老爹" {
        willSet {
            print("老爹willSet newValue = \(newValue) ")
        }
        didSet {
            print("老爹didSet oldValue = \(oldValue) ")
        }
    }
   
}

class SubArtOS: GitArtOS {
    
    override var content: String {
        willSet {
            print("儿子willSet newValue = \(newValue) ")
        }
        didSet {
            print("儿子didSet oldValue = \(oldValue) ")
        }
    }
}
var subson = SubArtOS()
subson.content = "子类和父类的计算属性同时存在didSet、willSet时，调用顺序探索"

执行顺序如下：

儿子willSet newValue = 子类和父类的计算属性同时存在didSet、willSet时，调用顺序探索 
老爹willSet newValue = 子类和父类的计算属性同时存在didSet、willSet时，调用顺序探索 
老爹didSet oldValue = 我是老爹 
儿子didSet oldValue = 我是老爹 
Program ended with exit code: 0