Swift 编程技巧：轻松掌握 86 个实用代码片段，快速提升开发效率
Swift 编程基础
在开始学习 Swift 编程技巧之前，我们首先需要了解一些 Swift 编程的基础知识。Swift 是苹果公司于 2014 年推出的编程语言，用于开发 iOS、macOS、watchOS 和 tvOS 应用。以下是 Swift 编程的一些基础知识：
数据类型
Swift 提供了丰富的数据类型，包括整型、浮点型、布尔型、字符串、数组、字典等。以下是一些常用的数据类型：
- 整型：Int、Int8、Int16、Int32、Int64
- 浮点型：Double、Float
- 布尔型：Bool
- 字符串：String
- 数组：Array
- 字典：Dictionary
控制流
Swift 提供了丰富的控制流语句，如 if 语句、switch 语句、循环语句等。以下是一些常用的控制流语句：
- if 语句
- switch 语句
- for 循环
- while 循环
函数和闭包
Swift 支持函数和闭包的概念。函数是一段可以重复调用的代码块，闭包则是一种更灵活的函数。以下是一些常用的函数和闭包：
- 函数：定义函数、调用函数
- 闭包：定义闭包、使用闭包
实用代码片段
以下是 86 个实用的 Swift 代码片段，可以帮助你快速提升开发效率：
1. 字符串操作
let name = "张三"
print(name.count) // 输出字符串长度
print(name.replacingOccurrences(of: "三", with: "四")) // 替换字符串中的字符
2. 数组操作
var numbers = [1, 2, 3, 4, 5]
print(numbers[0]) // 获取数组第一个元素
numbers.append(6) // 向数组中添加元素
print(numbers.count) // 获取数组长度
3. 字典操作
var person = ["name": "张三", "age": 18]
print(person["name"]) // 获取字典中的值
person["age"] = 19 // 更新字典中的值
4. 控制流
let score = 90
if score >= 90 {
print("优秀")
} else if score >= 80 {
print("良好")
} else {
print("及格")
}
5. 循环语句
for i in 1...5 {
print(i)
}
6. 函数
func greet(name: String) {
print("你好，\(name)！")
}
greet(name: "张三")
7. 闭包
let closure = { (name: String) -> String in
return "你好，\(name)！"
}
print(closure("李四"))
8. 类和对象
class Person {
var name: String
init(name: String) {
self.name = name
}
}
let person = Person(name: "王五")
print(person.name)
9. 属性和属性观察器
class Person {
var name: String {
didSet {
print("姓名已更新：\(name)")
}
}
init(name: String) {
self.name = name
}
}
let person = Person(name: "赵六")
person.name = "钱七"
10. 枚举
enum Weekday {
case monday, tuesday, wednesday, thursday, friday, saturday, sunday
}
let today = Weekday.tuesday
switch today {
case .monday:
print("星期一")
case .tuesday:
print("星期二")
// ... 其他情况
}
11. 协议和扩展
protocol Animal {
func eat()
}
extension Animal {
func sleep() {
print("睡觉")
}
}
class Dog: Animal {
func eat() {
print("吃狗粮")
}
}
let dog = Dog()
dog.eat()
dog.sleep()
12. 错误处理
enum MyError: Error {
case invalidInput
}
func divide(_ a: Int, _ b: Int) throws -> Int {
guard b != 0 else {
throw MyError.invalidInput
}
return a / b
}
do {
let result = try divide(10, 0)
print(result)
} catch {
print("错误：\(error)")
}
13. 异步编程
func fetchData(completion: @escaping (String) -> Void) {
DispatchQueue.global().async {
sleep(2)
let data = "获取数据成功"
DispatchQueue.main.async {
completion(data)
}
}
}
fetchData { data in
print(data)
}
14. 自定义布局
class MyViewController: UIViewController {
let myLabel = UILabel()
override func viewDidLoad() {
super.viewDidLoad()
myLabel.text = "自定义布局"
myLabel.textAlignment = .center
myLabel.frame = CGRect(x: 0, y: 100, width: 300, height: 50)
self.view.addSubview(myLabel)
}
}
15. 持续集成
import XCTest
class MyTestCase: XCTestCase {
func testExample() {
XCTAssertEqual(1 + 1, 2)
}
}
XCTMain([TestCaseCase("MyTestCase")])
16. 使用 SwiftUI
import SwiftUI
struct ContentView: View {
var body: some View {
Text("Hello, SwiftUI!")
}
}
@main
struct MyApp: App {
var body: some Scene {
WindowGroup {
ContentView()
}
}
}
17. 使用 Core Data
import CoreData
class MyEntity: NSManagedObject {
@NSManaged var name: String
}
let context = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
let entity = NSEntityDescription.entity(forEntityName: "MyEntity", in: context)!
let myEntity = MyEntity(entity: entity, insertInto: context)
myEntity.name = "张三"
context.save()
18. 使用 AVFoundation
import AVFoundation
let audioSession = AVAudioSession.sharedInstance()
try audioSession.setCategory(.playback, mode: .default)
try audioSession.setActive(true)
let audioPlayer = AVAudioPlayer()
let audioURL = Bundle.main.url(forResource: "audio", withExtension: "mp3")!
try audioPlayer.initWithContentsOf(audioURL, fileType: AVFileType.mp3)
audioPlayer.play()
19. 使用 Core Graphics
import CoreGraphics
let context = CGContext(data: nil, width: 100, height: 100, bitsPerComponent: 8, bytesPerRow: 0, space: CGColorSpaceCreateDeviceRGB(), bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue)!
context.setLineWidth(5)
context.setStrokeColor(UIColor.red.cgColor)
context.addLines(between: [(10, 10), (90, 10), (50, 90)])
context.strokePath()
20. 使用 Core ML
import CoreML
let model = try? MLModel.load("ModelName")
let input = [Double](repeating: 1.0, count: 10)
let output = try? model?.prediction(input: input)
print(output)
21. 使用 Core Location
import CoreLocation
let locationManager = CLLocationManager()
locationManager.requestAlwaysAuthorization()
locationManager.desiredAccuracy = kCLLocationAccuracyBest
locationManager.startUpdatingLocation()
22. 使用 HealthKit
import HealthKit
let healthKit = HKHealthStore()
healthKit.requestAuthorization(toShare: [HKCategoryType.quantityType(forIdentifier: .stepCount)!], read: [HKCategoryType.quantityType(forIdentifier: .stepCount)!]) { (success, error) in
if success {
let query = HKSampleQuery(sampleType: HKCategoryType.quantityType(forIdentifier: .stepCount)!, predicate: nil, limit: 0, sortDescriptors: nil) { (query, results, error) in
if let results = results as? [HKQuantitySample] {
for sample in results {
print(sample.quantity)
}
}
}
healthKit.execute(query)
}
}
23. 使用 Core Animation
import CoreAnimation
let animation = CABasicAnimation(keyPath: "transform.translation.x")
animation.toValue = 100
animation.duration = 2
animation.timingFunction = CAMediaTimingFunction(name: .easeInEaseOut)
animation.autoreverses = true
animation.repeatCount = Float.infinity
let layer = CALayer()
layer.frame = CGRect(x: 0, y: 0, width: 100, height: 100)
layer.backgroundColor = UIColor.red.cgColor
layer.add(animation, forKey: nil)
24. 使用 SceneKit
import SceneKit
let sceneView = SCNView()
sceneView.scene = SCNScene()
sceneView.frame = self.view.bounds
let sphereNode = SCNSphere(radius: 0.5)
let material = SCNMaterial()
material.diffuse.contents = UIColor.red
sphereNode.materials = [material]
let sphereGeometry = SCNGeometry(sphere: sphereNode)
sceneView.scene.rootNode.addChildNode(sphereNode)
25. 使用 MapKit
import MapKit
let map = MKMapView(frame: self.view.bounds)
self.view.addSubview(map)
let annotation = MKPointAnnotation()
annotation.coordinate = CLLocationCoordinate2D(latitude: 39.916527, longitude: 116.397128)
map.addAnnotation(annotation)
26. 使用 ARKit
import ARKit
let sceneView = ARSCNView(frame: self.view.bounds)
self.view.addSubview(sceneView)
let configuration = ARWorldTrackingConfiguration()
sceneView.session.run(configuration)
27. 使用 WatchKit
import WatchKit
let interfaceController = WKInterfaceController()
interfaceController.title = "我的应用"
interfaceController.addSeparator()
let label = WKLabel()
label.setText("你好，WatchOS！")
interfaceController.add(label)
28. 使用 WatchConnectivity
import WatchConnectivity
let session = WCSession.default
session.delegate = self
session.activate()
29. 使用 Network
import Network
let network = NWPathMonitor()
network.pathUpdateHandler = { path in
if path.status == .satisfied {
print("网络已连接")
} else {
print("网络未连接")
}
}
network.startMonitoring()
30. 使用 SQLite
import SQLite
let db = try Connection("path/to/database.sqlite3")
let people = Table("people")
let id = Expression<Int>("id")
let name = Expression<String>("name")
try db.run(people.create(ifNotExists: true))
let insert = people.insert(name <- "张三")
try db.run(insert)
31. 使用 FMDB
import FMDB
let database = FMDatabase(path: "path/to/database.sqlite")
database.open()
let statement = "SELECT * FROM people"
let resultSet = database.executeQuery(statement, withArgumentsIn: nil)
while resultSet.next() {
let name = resultSet.string(forColumn: "name")
print(name)
}
database.close()
32. 使用 Realm
import RealmSwift
let realm = try Realm()
let person = Person()
person.name = "李四"
try realm.write {
realm.add(person)
}
33. 使用 CoreData
import CoreData
let context = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
let entity = NSEntityDescription.entity(forEntityName: "Person", in: context)!
let person = NSManagedObject(entity: entity, insertInto: context)
person.setValue("王五", forKey: "name")
context.save()
34. 使用 Alamofire
import Alamofire
Alamofire.request("https://api.example.com").responseJSON { response in
print(response.result.value)
}
35. 使用 SwiftyJSON
import SwiftyJSON
let json = JSON(["name": "张三", "age": 18])
print(json["name"].string!) // 输出 "张三"
print(json["age"].int!) // 输出 18
36. 使用 Kingfisher
import Kingfisher
let imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
imageView.kf.setImage(with: URL(string: "https://api.example.com/image"))
self.view.addSubview(imageView)
37. 使用 AlamofireImage
import AlamofireImage
imageView.af_setImage(withURL: URL(string: "https://api.example.com/image"))
self.view.addSubview(imageView)
38. 使用 SDWebImage
imageView.sd_setImage(with: URL(string: "https://api.example.com/image"))
self.view.addSubview(imageView)
39. 使用 AFNetworking
import AFNetworking
let manager = AFHTTPSessionManager()
manager.request(.GET, "https://api.example.com").responseJSON { response in
print(response.result.value)
}
40. 使用 Reachability
import Reachability
let reachability = Reachability()
reachability?.whenReachable = { reachability in
if reachability!.isOnline {
print("网络已连接")
} else {
print("网络未连接")
}
}
reachability?.startNotifier()
41. 使用 ObjectMapper
import ObjectMapper
struct Person: Mapable {
var name: String?
var age: Int?
init?(map: Map) {
name <- map["name"]
age <- map["age"]
}
mutating func mapping(map: Map) {
name <- map["name"]
age <- map["age"]
}
}
let json = JSON(["name": "张三", "age": 18])
let person = Person(map: json)
print(person?.name) // 输出 "张三"
print(person?.age) // 输出 18
42. 使用 SwiftSoup
import SwiftSoup
let html = "<html><body><p>这是一个段落。</p></body></html>"
let document = try! SwiftSoup.parse(html)
let paragraph = try! document.select("p").first()
let text = try! paragraph.text()
print(text) // 输出 "这是一个段落。"
43. 使用 SwiftHTTP
import SwiftHTTP
let request = HTTPRequest(url: URL(string: "https://api.example.com")!, method: .GET)
request.start { response in
print(response.data)
}
44. 使用 URLSession
import Foundation
let url = URL(string: "https://api.example.com")!
let task = URLSession.shared.dataTask(with: url) { data, response, error in
if let data = data {
print(String(data: data, encoding: .utf8)!)
}
}
task.resume()
45. 使用 PromiseKit
import PromiseKit
func fetchData() -> Promise<String> {
return Promise { seal in
DispatchQueue.global().asyncAfter(deadline: .now() + 2) {
seal.fulfill("获取数据成功")
}
}
}
fetchData().done { data in
print(data)
}
46. 使用 FutureKit
import FutureKit
func fetchData() -> Future<String> {
return Future { seal in
DispatchQueue.global().asyncAfter(deadline: .now() + 2) {
seal.resolve("获取数据成功")
}
}
}
fetchData().onResolve { data in
print(data)
}
47. 使用 RxSwift
import RxSwift
let disposeBag = DisposeBag()
let observable = Observable.of("张三", "李四", "王五")
observable.subscribe(onNext: { name in
print(name)
}).disposed(by: disposeBag)
48. 使用 RxCocoa
import RxCocoa
let textField = UITextField()
let text = textField.rx.text.asObservable()
text.subscribe(onNext: { text in
print(text)
}).disposed(by: disposeBag)
49. 使用 ReactiveSwift
import ReactiveSwift
let textField = UITextField()
let text = textField.rx.text
text.observe(on: MainScheduler.instance).subscribe(onNext: { text in
print(text)
}).dispose()
50. 使用 RxAlamofire
import RxSwift
import Alamofire
let request = Alamofire.request("https://api.example.com")
request.responseData().subscribe(onNext: { data in
print(String(data: data, encoding: .utf8)!)
}).dispose()
51. 使用 URLSession
import Foundation
let url = URL(string: "https://api.example.com")!
let task = URLSession.shared.dataTask(with: url) { data, response, error in
if let data = data {
print(String(data: data, encoding: .utf8)!)
}
}
task.resume()
52. 使用 PromiseKit
import PromiseKit
func fetchData() -> Promise<String> {
return Promise { seal in
DispatchQueue.global().asyncAfter(deadline: .now() + 2) {
seal.fulfill("获取数据成功")
}
}
}
fetchData().done { data in
print(data)
}
53. 使用 FutureKit
import FutureKit
func fetchData() -> Future<String> {
return Future { seal in
DispatchQueue.global().asyncAfter(deadline: .now() + 2) {
seal.resolve("获取数据成功")
}
}
}
fetchData().onResolve { data in
print(data)
}
54. 使用 RxSwift
import RxSwift
let disposeBag = DisposeBag()
let observable = Observable.of("张三", "李四", "王五")
observable.subscribe(onNext: { name in
print(name)
}).disposed(by: disposeBag)
55. 使用 RxCocoa
”`swift import RxCocoa
let textField = UITextField() let text = textField.rx.text.asObservable()
text.subscribe(onNext: { text in
print(text)
}).disposed(by: disposeBag) “