swift - 基础属性 - 属性写法

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var num1 : Int = 0   var num2 : Int = 5   /// 1.计算属性 var num3 : Int{     return num1 + num2 }   /// 2.闭包属性 private lazy var num4 : Int = {    return num1 + num2 }()   override func viewDidLoad() {     super.viewDidLoad()     print(num3)     print(num4) }

　　

 

 

 

 

2.类属性

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class Student: NSObject {     /// 类属性     static var score : Int = 0 }         override func viewDidLoad() {         super.viewDidLoad()           Student.score = 1         print(Student.score)     }

　　

3. 对象属性赋值

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class Student: NSObject {           var age:Int = 0           ///可选属性： name1 和name2一个意思     var name1:String?     var name2:String? = nil }           let stu = Student()         stu.age = 10         stu.name1 = "1蛋"         stu.name2 = "2蛋"         print(stu.age)                   /// 可选属性 解包写法1         if let name = stu.name1{             print(name)         }                   /// 可选属性 解包写法2         guard let name2 = stu.name2 else { return }         print(name2)

                /// 可选属性 解包写法3

                print(stu.name1 ?? "")

 

 

　　

4.构造函数:   init(){}  是系统默认的构造函数

自定义构造函数：A> 旧语法 可以在 init的()里面直接写上新参数，B>: 在目前3.0后需要加上convenienceclass  

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class Student: NSObject {           var age:Int = 0           ///可选属性： name1 和name2一个意思     var name1:String?     var name2:String? = nil           /// 系统默认构造函数： 不需要写 self.init()，但是没啥用     override  init() {         self.name1 = "0"     }           /**自定义构造函数      *  age 和 age1一样，      *  使用conveniences需要写上self.init()      */     init(age:Int, name:String) {         self.age = age         self.name1 = name     }           convenience init(age1:Int, name1:String) {         self.init()         self.age = age1         self.name1 = name1     }           /**2.传入字典      *  dict，dict1，dict2，dict3一样，      *  dict2，dict3在使用时还是字典使用[String:Any]      */     init(dict:[String:Any]) {         self.age = dict["age"] as? Int ?? 0         self.name1 = dict["name1"] as? String ?? ""     }           convenience init(dict1:[String:Any]) {         self.init()         self.age = dict1["age"] as? Int ?? 0         self.name1 = dict1["name1"] as? String ?? ""     }           init(dict2:Dictionary<String, Any>) {         self.age = dict2["age"] as? Int ?? 0         self.name1 = dict2["name1"] as? String ?? ""     }           convenience init(dict3:Dictionary<String, Any>) {         self.init()         self.age = dict3["age"] as? Int ?? 0         self.name1 = dict3["name1"] as? String ?? ""     }       }             let tempStu = Student(age: 10, name: "tempStu")         print("tempStu",tempStu.name1 ?? "", tempStu.age)// tempStu tempStu 10                   let tempStu1 = Student(age1: 11, name1: "tempStu1")         print("tempStu1",tempStu1.name1 ?? "", tempStu1.age)// tempStu1 tempStu1 11                   let stu = Student(dict: ["age":18, "name1":"stu"])         print("dict",stu.name1 ?? "", stu.age)// dict stu 18                   let stu1 = Student(dict1: ["age":18, "name1":"stu1"])         print("dict1",stu1.name1 ?? "", stu1.age)//dict1 stu1 18                   let stu2 = Student(dict2: ["age":18, "name1":"stu2"])         print("dict2",stu2.name1 ?? "", stu2.age)//dict2 stu2 18                   let stu3 = Student(dict3: ["age":18, "name1":"stu3"])         print("dict3",stu3.name1 ?? "", stu3.age)//dict3 stu3 18