swift系统学习第三章

第九节:结构体-sturt

 //: Playground - noun: a place where people can play

 import UIKit

 /*
 swift学习第九节
 结构体:sturt
 */
 let centerX = 100.0
 let centerY = 100.0
 let distance = 200.0
 //定义结构体sturt
 struct Location {
     var x : Double =
     var y : Double = 

     //结构体初始化
     init (StringPoint:String){
        let xy = StringPoint.characters.split(",")
         x = atof(String(xy.first!))
         y = atof(String(xy.last!))

     }
     init(x:Double,y:Double){
        self.x = x
        self.y = y
     }
     init(){}

     mutating func move2(dist:Double){
        self.x += dist

     }

 }

 var pointA = Location(x: , y: )
 let pointB = Location(StringPoint: "100,200")
 let PointC = Location()
 pointA.x
 pointA.y
 pointB.x
 pointB.y

 //把结构体作为参数传入
 func inRange(point:Location) -> Bool {
    let distX = point.x - centerX
    let distY = point.y - centerY
    let dist = sqrt(pow(distX, ) + pow(distY,))
    return dist < distance
 }
 inRange(pointA)

 func move(dist:Double,inout point:Location){
    point.x += dist
 }
 move(, point: &pointA)
 pointA
 pointA.move2(100.0)

 //extension 扩展
 extension Location {
     mutating func move3(dist:Double){
        self.y += y
     }
 }
 pointA.move3()

 extension String {
     func isEven() -> Bool {
         return self.characters.count %  ==  ? true : false
     }
 }
 "An even string".isEven()

 var copyPointA = pointA
 copyPointA.y = 10000.0
 pointA    // struct 是值类型

第十节:
struct 和 class
       1. class 必须有init()方法
          struct 可以不写init()方法,默认有init方法
       2. struct 为值类型
          class 为引用类型

 //: Playground - noun: a place where people can play
 /*
 swift学习第十节
 struct 和 class
        1. class 必须有init()方法
           struct 可以不写init()方法,默认有init方法
        2. struct 为值类型
           class 为引用类型

 */
 import UIKit

 struct PointVal {
     var x: Int
     var y: Int
     init(x:Int,y:Int){
        self.x = x
        self.y = y
     }
     mutating func moveX(x:Int){
       self.x += x
     }
 }
 class PointRef {
     var x: Int
     var y: Int
     init(x:Int,y:Int){
         self.x = x
         self.y = y
     }
     func moveX(x:Int){
       self.x += x
     }
 }
 let p1 = PointVal(x: , y: )
 let p2 = PointRef(x: , y: )
 let p3 = PointRef(x: , y: )
 // p1.x = 10
 p2.x =     //这里,p1不能修改,但是p2可以修改.因为p2是引用类型,p1是值类型
 if p2 === p3 {
    print("他们是相同的对象")
 }
 if p2 !== p3{
    print("他们不是相同的对象")
 }

 var p4 = p1
 p4.x =
 p1.x

 var p5 = p2
 p5.x =
 p2.x

第十一节:
函数式
内存泄露:循环引用

 //: Playground - noun: a place where people can play

 import UIKit
 /*
 swift学习第十一节
 函数式
 内存泄露:循环引用

 */
 var number = [,,,,,]
 var event = [Int]()
 for n in number {
     if n %  == {
        event.append(n)
     }
 }
 event

 let evens1 = number.filter({(n:Int) -> Bool in return n %  == })
 evens1

 //-------------------------------内存管理--------------------
 class Person {
     let name:String
     init(name:String){
        self.name = name
        print("\(name) 被构建")
     }
     deinit{
        print("\(name) 被销毁")
     }
 }
 var ref1:Person?
 var ref2:Person?

 ref1 = Person(name: "Tom")   //Person对象的引用计数为1
 ref2 = ref1                //Person对象的引用计数为2
 ref1 = nil                 //Person对象的引用计数为1
 ref2 = nil                 //deinit()方法被执行

 //循环引用造成的内存泄露
 class Student {
     let name:String
     var apartment:School?
     init(name:String){
        self.name = name
         print("\(name)被创建")
     }
     deinit{
         print("\(name)被销毁");
     }
 }
 class School {
     let unit: String
     var tenant: Student?
     init(unit:String){
       self.unit = unit
       print("\(unit)被创建")
     }
     deinit{
        print("\(unit)被销毁")
     }
 }
 var tom:Student? = Student(name: "TOM")
 var apt11:School? = School(unit: "")

 //tom!.apartment = apt11   //这两句会造成循环引用
 //apt11!.tenant  = tom

 tom = nil
 apt11 = nil

第十二节:

reference cycle 的方式
1.使用weak   使用weak,不会造成引用计数+1,如果没有指向任何对象,则自动设置为nil
   场景:双方均可以为空
2.umowned
   场景:一方可以为空

 //: Playground - noun: a place where people can play
 /*
 reference cycle 的方式
 1.使用weak   使用weak,不会造成引用计数+1,如果没有指向任何对象,则自动设置为nil
    场景:双方均可以为空
 2.umowned
    场景:一方可以为空

 */

 import UIKit

 //循环引用造成的内存泄露
 class Student {
     let name:String
     var apartment:School?
     init(name:String){
         self.name = name
         print("\(name)被创建")
     }
     deinit{
         print("\(name)被销毁");
     }
 }
 class School {
     let unit: String
     weak  var tenant: Student?
     init(unit:String){
         self.unit = unit
         print("\(unit)被创建")
     }
     deinit{
         print("\(unit)被销毁")
     }
 }
 var tom:Student? = Student(name: "TOM")
 var apt11:School? = School(unit: "")

 tom!.apartment = apt11   //这两句会造成循环引用
 apt11!.tenant  = tom

 tom = nil
 apt11 = nil

源码下载地址:

http://download.csdn.net/detail/shaoting19910730/9470584

https://github.com/pheromone/swift3