/// 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()
}
}
时间： 2024-08-04 17:01:43