突然兴起复习一下Swift3.0

Posted 2020-08-21 ITCoderW

/// 参考Swift3.0.1文档
/// 摘录来自: Apple Inc. “The Swift Programming Language (Swift 3.0.1)”。 iBooks.

import UIKit


class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        aSwiftTour()
        
    }
    
    func aSwiftTour(){
        //Swift中的输出语句
        print("Hello World")
        
        //MARK: - 变量
        /**var声明变量
         Swift具备自动推导的能力
         右边是什么类型这个变量或者是常量就自动的是什么类型了
        */
        var variable = 66
        variable = 88
        //MARK: - let声明常量
        let constant = 66
        print(variable,constant)
        
        //指定变量的类型 隐式指定
        let implictInteger = 66     //Int
        let implicitDouble = 66.0   //Double
        
        //显式地指定类型为Double
        let explicitDouble: Double = 88 //Double
        print(implictInteger,implicitDouble,explicitDouble)
        
        
        let label = "The width is"
        let width = 94
        let widthLabel = label + String(width)
        print(widthLabel)
        
        //MARK: - 数字和字符串的拼接
        let apples = 3
        let oranges = 5
        let appleSummary = "I have \(apples) apples."
        let fruitSummary = "I have \(apples + oranges) pieces of fruit."
        
        //MARK: - 数组操作
        var shoppingList = ["catfish", "water", "tulips", "blue paint"]
        shoppingList[1] = "bottle of water"
        
        //MARK: - 字典操作 key:value
        var occupations = [
            "Malcolm": "Captain",
            "Kaylee": "Mechanic",
            ]
        occupations["Jayne"] = "Public Relations"
        
        
        //创建空数组和空字典的方式  
        //创建一个元素类型为字符串的数组
        let emptyArray = [String]()
        //key为String类型value为Float类型的字典
        let emptyDictionary = [String: Float]()
        
        
        //MARK: - 数组字典更简单的方式
        /**
         “If type information can be inferred, you can write an empty array as [] and an empty dictionary as [:]—for example, when you set a new value for a variable or pass an argument to a function.”
         摘录来自: Apple Inc. “The Swift Programming Language (Swift 3.0.1)”。 iBooks.
         */
        shoppingList = []//默认是[String]
        occupations = [:]//默认是[String:String]
        
        
         //MARK: - 控制流 
        //注意for if else 的格式
        let individualScores = [75, 43, 103, 87, 12]
        var teamScore = 0
        for score in individualScores {
            if score > 50 {
                teamScore += 3
            } else {
                teamScore += 1
            }
        }
        print(teamScore)
        
        
         //MARK: - ?是可选值类型
        var optionalString: String? = "Hello"
        print(optionalString == nil)
        
        var optionalName: String? = "John Appleseed"
        
        var greeting = "Hello!"
        if let name = optionalName {
            greeting = "Hello, \(name)"
            
        }
        
        
        //MARK: - “Another way to handle optional values is to provide a default value ”“using the ?? operator. If the optional value is missing, the default value is used instead.”
    
        let nickName: String? = nil
        let fullName: String = "John Appleseed"
        let informalGreeting = "Hi \(nickName ?? fullName)"
        
        /**
         (lldb) po nickName
         nil
         
         (lldb) po fullName
         "John Appleseed"
         
         (lldb) po informalGreeting
         "Hi John Appleseed"
         */
        
        
         //MARK: - Switch Case的用法
        let vegetable = "red pepper"
        switch vegetable {
        case "celery":
            print("Add some raisins and make ants on a log.")
        case "cucumber", "watercress":
            print("That would make a good tea sandwich.")
            
            //用x来标识vegetable 看看这个字符串的尾部是否有pepper   Returns a Boolean value indicating whether the string ends with the specified suffix.
        case let x where x.hasSuffix("pepper"):
            print("Is it a spicy \(x)?")
            //Is it a spicy red pepper?
            
        default:
            print("Everything tastes good in soup.")
            
        }
        
        
        
        
         //MARK: - 快速遍历数组 并且找出来最大值
        /**
         三个字典还是鄙视比较好玩的 素数 斐波那契数列 平方
         */
        let interestingNumbers = [
            "Prime": [2, 3, 5, 7, 11, 13],
            "Fibonacci": [1, 1, 2, 3, 5, 8],
            "Square": [1, 4, 9, 16, 25],
            ]
        var largest = 0
        for (kind, numbers) in interestingNumbers {
            for number in numbers {
                if number > largest {
                    largest = number
                }
            }
        }
        print(largest)  //25
        
        
        //MARK: - 循环
        var n = 2
        while n < 100 {
            n = n * 2
        }
        print(n)
        //128
        var m = 2
        //就类似于do while
        repeat {
            m = m * 2
        } while m < 100
        print(m)
        
        //128
        
        /**
         
        “Use ..< to make a range that omits its upper value, and use ... to make a range that includes both values.”
         */
        
        
        var total = 0
        for i in 0..<4 {
            total += i //1 2 3
        }
        
        print(total)//6
        
        
        var totalBoth = 0
        for i in 0...4 {
            totalBoth += i//1 2 3 4
        }
        print(totalBoth)//10

        
         //MARK: - 函数和闭包
        //函数            函数参数                    返回值
        func greet(person: String, day: String) -> String {
            return "Hello \(person), today is \(day)."
        }
        let s = greet(person: "Bob", day: "Tuesday")
        
        //"Hello Bob, today is Tuesday."
        
        func calculateStatistics(scores: [Int]) -> (min: Int, max: Int, sum: Int) {
            var min = scores[0]
            var max = scores[0]
            var sum = 0
            
            for score in scores {
                if score > max {
                    max = score
                } else if score < min {
                    min = score
                }
                sum += score
            }
            
            return (min, max, sum)
        }
        let statistics = calculateStatistics(scores: [5, 3, 100, 3, 9])
        print(statistics.sum)
        print(statistics.2)
        //120  120
        /**
         (lldb) po statistics.min
         3
         
         
         (lldb) po statistics.max
         100
         
         
         (lldb) po statistics.sum
         120
         */
        
         //可变参数的函数 zhu‘yi
        func sumOf(numbers: Int...) -> Int {
            var sum = 0
            for number in numbers {
                sum += number
            }
            return sum
        }
        let sumOfEmptyParam = sumOf()
        
        let sumOfThree = sumOf(numbers: 42, 597, 12)
       
        
        /**
         (lldb) po sumOfEmptyParam
         0
         
         
         (lldb) po sumOfThree
         651
         */
        
        //函数A的内部有函数B 函数A内部还调用了函数B
        func returnFifteen() -> Int {
            var y = 10
            func add() {
                y += 5
            }
            add()
            return y
        }
        
        let fifteenFunc = returnFifteen()   //15
        
        
        //参数为空 返回值为闭包类型
        func makeIncrementer() -> ((Int) -> Int) {
            //参数为整型  返回值为整数
            func addOne(number: Int) -> Int {
                return 1 + number
            }
            return addOne
        }
        var increment = makeIncrementer()
        increment(7) //8
        
        
        //“A function can take another function as one of its arguments.
        //函数的返回值是一个函数 而且不仅仅是一个函数那么简单 只可意会哈哈
        func hasAnyMatches(list: [Int], condition: (Int) -> Bool) -> Bool {
            for item in list {
                if condition(item) {
                    return true
                    
                }
            }
            return false
        }
        func lessThanTen(number: Int) -> Bool {
            return number < 10
        }
        var numbers = [20, 19, 7, 12]
        let nubersB = hasAnyMatches(list: numbers, condition: lessThanTen)
        
        
        //true 7满足条件
        print(nubersB)
        
        
         //MARK: - 闭包
        //“You can write a closure without a name by surrounding code with braces ({}). ”
        //到了闭包了 先停一下??
        
        numbers.map({
            (number: Int) -> Int in
            let result = 3 * number
            return result
            })
        
      
        
        
    
    }
    
    
    
    
    

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        
    }


}