1.函数的定义与使用
//求两个数之和的函数
//函数定义
//格式:func 函数名 （形参列表） -> 返回值类型 { 函数体}
func sum (number1:Int, number2:Int) -> Int{
return number1 + number2;
}
//函数的使用
let sumTwoNubmer = sum(2, number2: 3);
2.函数的形参的注意点
2.1默认形参是常量,若要在函数中对形参改变,在形参前加上var修饰
2.2给参数添加一个名字,调用函数的时候就一目了然
func sum (numberone number1:Int,numbertwo number2:Int) ->Int {
return number1 + number2;
}
let sum1 = sum(numberone: 1, numbertwo: 3)
print(sum1)
2.3形参的址传递:用inout 修饰形参,调用的时候用&
func test1 (inout number: Int) -> Int {
number++
return number;
}
var addtestNumber = 10;
let addnum = test1(&addtestNumber); //结果:11
print(addnum) //结果:11
print(addtestNumber) //结果:11
2.4不定参数函数
说明:形参的个数是不定的，但是形参的类型必须是相同的,不定个数的形参实际上是一个数组
1451876890323984.png
2.5默认形参:每个参数都是有名字的,调用函数的时候,可以给任意一个参数赋值,其他的就去默认值
func love (name1:String = "山伯",name2: String = "英台") {
print("\(name1) love \(name2)")
}
love()
love("梁山伯")
love("梁山伯", name2: "祝英台")
3.函数类型:如果几个函数参数列表相同以及返回值类型相同，那么这两个函数就有着相同的函数类型。
//定义枚举
enum Type: Int{
case jia = 0
case cheng
}
//3.函数类型
func jia (n1: Int,n2: Int) -> Int{
return n1 + n2;
}
func cheng (n1: Int,n2: Int) -> Int{
return n1 * n2;
}
func typeName(type:Type) -> ((Int,Int) -> Int) {
var myfunc: (Int,Int) -> Int
switch type {
case .jia:
myfunc = jia
case .cheng:
myfunc = cheng
}
return myfunc
}
var myfunc: (Int,Int) -> Int
myfunc = typeName(Type.cheng)
print(myfunc(1,2))
myfunc = typeName(Type.jia)
print(myfunc(1,2))
4.函数嵌套
func typeName(type:Type) -> ((Int,Int) -> Int) {
func jia (n1: Int,n2: Int) -> Int{
return n1 + n2;
}
func cheng (n1: Int,n2: Int) -> Int{
return n1 * n2;
}
var myfunc: (Int,Int) -> Int
switch type {
case .jia:
myfunc = jia
case .cheng:
myfunc = cheng
}
return myfunc
}
5.闭包:等同于OC中的block
5.1定义
var myCloure0:((Int, Int) -> Int)?
//或者
typealias MyClosureType = (Int, Int) -> Int
var myCloure:MyClosureType?
5.2应用
说明:A控制器有两个控件,Lable和按钮,B控制器有三个控件,textfield和俩按钮,点击A按钮进入B控制器,在B控制的textfield中输入字符串,点击确定按钮把textfield中的字符串在A控制器的lable中显示,或者点击返回按钮直接返回
//A控制器--ViewController
// Created by Vanessa on 16/3/29.
// Copyright © 2016年 Vanessa. All rights reserved.
//
import UIKit
class ViewController: UIViewController {
var showLable: UILabel?
var pushBtn: UIButton?
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
//1. 添加lable控件
showLable = UILabel.init(frame: CGRectMake((UIScreen.mainScreen().bounds.size.width - 200) * 0.5, 100, 200, 44))
showLable?.backgroundColor = UIColor.blueColor()
self.view.addSubview(showLable!)
//2. 添加按钮控件
pushBtn = UIButton.init(type: UIButtonType.Custom)
pushBtn?.frame = CGRectMake((UIScreen.mainScreen().bounds.size.width - 200) * 0.5, 200, 200, 44)
pushBtn?.backgroundColor = UIColor.grayColor()
pushBtn?.setTitle("跳转到下一界面", forState: UIControlState.Normal)
pushBtn?.titleLabel?.textColor = UIColor.whiteColor()
pushBtn?.addTarget(self, action: Selector.init(stringLiteral: "pushToSectionVC"), forControlEvents: UIControlEvents.TouchUpInside)
self.view.addSubview(pushBtn!)
// self.view.backgroundColor = UIColor.redColor()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
//MARK: - event
func pushToSectionVC() {
let secVC: SecondViewController = SecondViewController()
secVC.setMyblock {(str: String) -> Void in
self.showLable?.text = str
}
self.presentViewController(secVC, animated:true, completion: nil)
}
}
//B控制器--SecondViewController
import UIKit
class SecondViewController: UIViewController {
var myBlock: ((str:String) -> Void)?
var textField: UITextField?
var backBtn: UIButton?
var sureBtn: UIButton?
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
self.view.backgroundColor = UIColor.whiteColor()
textField = UITextField.init(frame: CGRectMake((UIScreen.mainScreen().bounds.size.width - 100) * 0.5, 100, 100, 44))
textField?.backgroundColor = UIColor.greenColor()
self.view.addSubview(textField!)
backBtn = UIButton.init(frame: CGRectMake(50, 200, 60, 40))
backBtn?.setTitle("返回", forState: UIControlState.Normal)
backBtn?.backgroundColor = UIColor.blueColor()
backBtn?.addTarget(self, action: Selector.init(stringLiteral: "back"), forControlEvents: UIControlEvents.TouchUpInside)
self.view.addSubview(backBtn!)
sureBtn = UIButton.init(frame: CGRectMake(200, 200, 60, 40))
sureBtn?.setTitle("确定", forState: UIControlState.Normal)
sureBtn?.backgroundColor = UIColor.blueColor()
sureBtn?.addTarget(self, action: Selector.init(stringLiteral: "sure"), forControlEvents: UIControlEvents.TouchUpInside)
self.view.addSubview(sureBtn!)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func setMyblock(tempBlock: (str:String) -> Void) {
self.myBlock = tempBlock
}
//MARK: - event
func back() {
self.dismissViewControllerAnimated(true, completion: nil)
}
func sure() {
if let string = textField?.text {
myBlock!(str: (textField?.text!)!)
self.dismissViewControllerAnimated(true, completion: nil)
}
}
}
效果图
viewController
SecondViewController
6.数组中常用的闭包函数
6.1映射(map)
let items = [1,2,3,4,5]
let strItems = items.map { (number: Int) -> String in
return ("我是\(number)号")
}
6.2过滤器(Filter)
let score = [98,88,69,100,85,77]
let grade = score.filter { (score: Int) -> Bool in
return score >= 85
}
print(grade) //[98, 88, 100, 85]
6.3Reduce
let totle = score.reduce(0) { (totleGrade: Int, everyGrade: Int) -> Int in
return totleGrade + everyGrade
}
print(totle) //结果:517
totleGrade + everyGrade每次的运算的结果曲线
