【iOS】—— swift基础语法及一些第三方库使用-Toy模板网

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swift基础语法

常量（let关键字）

只能赋值一次
它的值不要求在编译时期确定，但使用之前必须赋值一次

变量（var关键字）

可以被赋值多次
跟常量一样，在使用之前必须给他赋值，否则编译器会报错

var str:String
str = "hello world";
print(str)
str += " 11";
print(str)

var a, b, c:Int
a = 1
print(a)

var bool1:Bool = true
print(bool1)

元组

var pen:(name:String, price:Int) = ("英雄", 15);
pen.name = "毕加索"

var car:(String, Int) = ("奔驰", 9999)
car.0 = "宝马"
var (theName, thePrice) = car
print(theName, thePrice)

typealias（类似之前的typedef）

typealias Price = Int
var penPrice:Price = 100

if-let

var product:Int? = 100
if let weight = product, (weight > 30) {
    print("666")
}

String类基本用法

//String
var c1 = "hello"
var c2 = "world"
var c3 = c1 + " " + c2

var d1 = "hello\(123)"
var d2 = "hello\(c2)"
var d3 = "hello\(1+2)"
var d4 = "hello\(1) \(3)"
print(d1, d2, d3, d4)

var string2 = "My name is Jaki"
string2 = string2.uppercased()   //全部转化为大写
print(string2)
string2 = string2.lowercased()   //全部转化为小写
print(string2)
print(string2.hasPrefix("my"))
print(string2.hasSuffix("jaki"))

MemoryLayout(类比于c中的sizeof)

//MemoryLayout(类比于c中的sizeof)
print(MemoryLayout<String>.size)

数组

//数组
var array1:[Int]
var array2:Array<Int>

//创建有10个String类型元素的数组，并且每个元素都为字符串Hello
var array3 = [String](repeating: "hello", count: 10)
print(array3)
//同理的Int
var array4 = Array (repeating: 1, count: 10);
print(array4)
print(array4.contains(1))   //判断数组中是否包含某个元素
//数组排序
var arraySort = [1, 3, 5, 6, 7]
arraySort = arraySort.sorted(by: >)   //从大到小
arraySort = arraySort.sorted(by: <)   //从小到大
print(arraySort.max()!)   //获取数组中的最大值
print(arraySort.min()!)   //获取数组中的最小值

集合

//集合
var set1:Set<Int> = [1, 2, 3, 4]
var set2 = Set(arrayLiteral: 1, 2, 3, 4)
print(set1.isEmpty)
print(set1.contains(1))   //是否包含1
set1.insert(5)
set1.remove(1)
set1.removeFirst()
//set1.remove(at: set1.firstIndex(of: 2)!)   //移除集合中某个位置的元素
for item in set1.sorted(by: >) {
    print(item)   //从大到小排序再遍历集合
}

字典

//字典
var dic1:[Int: String]
var dic2:Dictionary<Int, String>
var dic3 = [1: "one"]
dic1 = [1:"1", 2:"2", 3:"3"]
dic2 = Dictionary(dictionaryLiteral: (1, "1"), (2, "2"), (3, "3"))

循环打印

//循环打印
for i in 1...7 {
    print(i, terminator: " ")
}

函数

//函数
func hanshu(param:Int) -> Int {
    return param + 1;
}

重载

func addFunc(param1:Int, param2:Int)->Int {
    return param1 + param2
}
func addFunc(param1:Double, param2:Double)->Double {
    return param1 + param2
}
func addFunc(param1:String, param2:String)->String {
    return param1 + param2
}
print(addFunc(param1: 5, param2: 10));
print(addFunc(param1: 1.52, param2: 3.61))
print(addFunc(param1: "123", param2: "abc"))

类和继承

//类和继承(final阻止继承和重写)
var car1 = Car(tyreCount: 4)
car1.drive()
var boat1 = Boat(floor: 50)
boat1.drive()

set、get方法

//set、get方法
let teacher = Teacher1()
teacher.memberAge = -1
teacher.memberName = ""
print(teacher.description)

SnapKit第三方库用法（Masonry）

这个第三方库和Masonry的作用和用法都很相似

            leftLabel.snp.makeConstraints { make in
                make.left.equalTo(self).offset(30)
                make.top.equalTo(self).offset(Int(SIZE_HEIGHT) / 5 + i * (Int(SIZE_WIDTH) / 6) + Int(SIZE_WIDTH) / 10)
                make.width.equalTo(SIZE_WIDTH / 10)
                make.height.equalTo(SIZE_WIDTH / 10)
            }

其中这块我们看到和oc不同的是Int(SIZE_HEIGHT)这块有个强制类型转化，这块原因是因为Swift是一个非常安全的语言，所以类型必须是相同的SIZE_WIDTH是一个浮点型常量，i是一个Int型变量，所以类型不同不能一起计算。

有了oc的基础，关于swift的学习比较容易，可以找一些项目练练手更好入手。

Codable（JSONModel）

这个库是官方的，不用导直接能用，用法和JSONModel类似，有一些小区别，但是感觉更好用一下：

    struct DailyNews: Codable {
        let date: String
        let stories: [Story]
        let topStories: [TopStory]

        enum CodingKeys: String, CodingKey {
            case date, stories
            case topStories = "top_stories"
        }
    }

    struct Story: Codable {
        let imageHue: String
        let title: String
        let url: String
        let hint: String
        let gaPrefix: String
        let images: [String]
        let type: Int
        let id: Int

        enum CodingKeys: String, CodingKey {
            case imageHue = "image_hue"
            case title, url, hint
            case gaPrefix = "ga_prefix"
            case images, type, id
        }
    }

    struct TopStory: Codable {
        let imageHue: String
        let hint: String
        let url: String
        let image: String
        let title: String
        let gaPrefix: String
        let type: Int
        let id: Int

        enum CodingKeys: String, CodingKey {
           case imageHue = "image_hue"
           case hint, url, image, title
           case gaPrefix = "ga_prefix"
           case type, id
       }
    }

    func netWorkWithData2(){
        if let urlString = URL(string: "https://news-at.zhihu.com/api/4/news/latest") {
            let request = URLRequest(url: urlString)
            URLSession.shared.dataTask(with: request) { data, response, error in
                        
                guard let httpResponse = response as? HTTPURLResponse, (200...299).contains(httpResponse.statusCode) else {
                    print("Invalid response")
                    return
                }
                            
                do {
                    let decoder = JSONDecoder()
                    //decoder.keyDecodingStrategy = .convertFromSnakeCase // 有需要则配置这个属性
                    let newsVersion = try decoder.decode(DailyNews.self, from: data!)
                    print(newsVersion.stories[0].title)
                } catch {
                    print(error.localizedDescription)
                }
                
            }.resume()
        }
    }

Alamofire (AFNetworking)

Alamofire.request("https://news-at.zhihu.com/api/4/news/latest").responseJSON { response in
            switch response.result {
                case .success(let value):
                    do {
                        let jsonData = try JSONSerialization.data(withJSONObject: value, options: [])
                        let decoder = JSONDecoder()
                        //decoder.keyDecodingStrategy = .convertFromSnakeCase
                        let latestNews = try decoder.decode(DailyNews.self, from: jsonData)
                        print(latestNews.stories[0].title)
                        // 解析成功，可以使用 latestNews 对象进行后续操作
                    } catch {
                        print(error)
                        // 解析错误，处理异常情况
                    }
                case .failure(let error):
                    // 请求失败
                    print(error)
                }
        }