ReactiveX 学习笔记（17）使用 RxSwift + Alamofire 调用 REST API
JSON : Placeholder
JSON : Placeholder (https://jsonplaceholder.typicode.com/) 是一个用于测试的 REST API 网站。
以下使用 RxSwift + Alamofire 调用该网站的 REST API，获取字符串以及 JSON 数据。
- GET /posts/1
- GET /posts
- POST /posts
- PUT /posts/1
- DELETE /posts/1
所有 GET API 都返回JSON数据，格式（JSON-Schema）如下：
{
"type":"object",
"properties": {
"userId": {"type" : "integer"},
"id": {"type" : "integer"},
"title": {"type" : "string"},
"body": {"type" : "string"}
}
}
创建工程
打开 Xcode，File / New / Project..
在 New Project 向导的第1页，选 iOS / Single View App
在向导的第2页填上 Product Name: RxExample
在向导的第3页选择任意文件夹点击 Create 按钮创建工程
关闭所创建的工程
配置 Pods
在工程所在文件夹下创建 Podfile 文件，内容如下：
workspace 'RxExample'
use_frameworks!
target 'RxExample' do
project 'RxExample'
pod 'CodableAlamofire'
pod 'RxAlamofire'
end
打开终端在工程所在文件夹下执行 pod install 命令。
$ cd RxExample
$ pod install
...
Installing Alamofire (4.7.3)
Installing CodableAlamofire (1.1.0)
Installing RxAlamofire (4.2.0)
Installing RxSwift (4.2.0)
...
用 Xcode 打开 RxExample.xcworkspace
RxCodableAlamofire
在 RxExample 工程中添加 RxCodableAlamofire.swift 文件，内容如下：
import Foundation
import RxSwift
import Alamofire
import RxAlamofire
import CodableAlamofire
class RxCodableAlamofire {
public static func object<T: Decodable>(_ method: Alamofire.HTTPMethod, _ url: URLConvertible, parameters: [String: Any]? = nil, encoding: ParameterEncoding = URLEncoding.default, headers: [String: String]? = nil, queue: DispatchQueue? = nil, keyPath: String? = nil, mapToObject object: T? = nil, decoder: JSONDecoder = JSONDecoder()) -> Observable<T> {
return SessionManager.default.rx.object(method, url, parameters: parameters, encoding: encoding, headers: headers, queue: queue, keyPath: keyPath, mapToObject: object, decoder: decoder)
}
}
extension Reactive where Base: SessionManager {
public func object<T: Decodable>(_ method: Alamofire.HTTPMethod, _ url: URLConvertible, parameters: [String: Any]? = nil, encoding: ParameterEncoding = URLEncoding.default, headers: [String: String]? = nil, queue: DispatchQueue? = nil, keyPath: String? = nil, mapToObject object: T? = nil, decoder: JSONDecoder = JSONDecoder()) -> Observable<T> {
return request(method, url, parameters: parameters, encoding: encoding, headers: headers).flatMap { $0.rx.object(queue: queue, keyPath: keyPath, mapToObject: object, decoder: decoder) }
}
}
extension Reactive where Base: DataRequest {
public func object<T: Decodable>(queue: DispatchQueue? = nil, keyPath: String? = nil, mapToObject object: T? = nil, decoder: JSONDecoder = JSONDecoder()) -> Observable<T> {
return result(queue: queue, responseSerializer: DataRequest.DecodableObjectSerializer(keyPath, decoder))
}
}
在 Pods 工程中找到并打开 DataRequest+Decodable.swift （Pods/CodableAlamofire）
将其中的 DecodableObjectSerializer 的可见性从 private 改为 public。(提示是否 unlock 时按下 Unlock)
RestApi
在 RxExample 工程中添加 RestApi.swift 文件，内容如下：
import Foundation
import Alamofire
import RxSwift
import RxAlamofire
// https://stackoverflow.com/questions/27855319/post-request-with-a-simple-string-in-body-with-alamofire
class StringEncoding: ParameterEncoding {
let body: String;
public init(body: String) {
self.body = body
}
public func encode(_ urlRequest: URLRequestConvertible, with parameters: Parameters?) throws -> URLRequest {
var request = try urlRequest.asURLRequest()
request.httpBody = body.data(using: .utf8, allowLossyConversion: false)
return request
}
}
extension Encodable {
public func toJSONString(prettyPrint: Bool) throws -> String? {
let encoder = JSONEncoder()
if prettyPrint { encoder.outputFormatting = .prettyPrinted }
let data = try! encoder.encode(self)
let jsonString = String(data: data, encoding: .utf8)
return jsonString
}
}
class RestApi {
static func getObject<T: Decodable>(url: String, keyPath: String? = nil) -> Observable<T> {
return RxCodableAlamofire.object(.get, url, keyPath: keyPath)
}
static func getArray<T: Decodable>(url: String, keyPath: String? = nil) -> Observable<[T]> {
return RxCodableAlamofire.object(.get, url, keyPath: keyPath)
}
static func update(url: String, body: String) -> Observable<String> {
return RxAlamofire.string(.put, url, encoding: StringEncoding(body: body))
}
static func create(url: String, body: String) -> Observable<String> {
return RxAlamofire.string(.post, url, encoding: StringEncoding(body: body))
}
static func delete(url: String) -> Observable<String> {
return RxAlamofire.string(.delete, url)
}
static func getString(url: String) -> Observable<String> {
return RxAlamofire.string(.get, url)
}
}
Post
在 RxExample 工程中添加 Post.swift 文件，内容如下：
import Foundation
import RxSwift
struct Post : Codable {
let userId: Int
let id: Int
let title: String
let body: String
var description: String {
return "Post {userId = \(userId), id = \(id), title = \"\(title)\", body = \"\(body.replacingOccurrences(of: "\n", with: "\\n"))\"}";
}
static let url = "https://jsonplaceholder.typicode.com/"
static func getPostAsString() -> Observable<String> {
return RestApi.getString(url: "\(url)posts/1")
}
static func getPostAsJson() -> Observable<Post> {
return RestApi.getObject(url: "\(url)posts/1")
}
static func getPosts(n: Int) -> Observable<Post> {
return RestApi.getArray(url: "\(url)posts").flatMap { Observable.from($0) }.take(n)
}
static func createPost() -> Observable<String> {
let post = Post(userId: 101, id: 0, title: "test title", body: "test body")
return RestApi.create(url: "\(url)posts", body: try! post.toJSONString(prettyPrint: false)!)
}
static func updatePost() -> Observable<String> {
let post = Post(userId: 101, id: 1, title: "test title", body: "test body")
return RestApi.update(url: "\(url)posts/1", body: try! post.toJSONString(prettyPrint: false)!)
}
static func deletePost() -> Observable<String> {
return RestApi.delete(url: "\(url)posts/1")
}
}
- getPostAsString 方法取出第1个Post，返回字符串
- getPostAsJson 方法取出第1个Post，返回Post对象
- getPosts 方法取出前n个Post，返回n个Post对象
- createPost 方法创建1个Post，返回字符串
- updatePost 方法更新第1个Post，返回字符串
- deletePost 方法删除第1个Post，返回字符串
AppDelegate
在 AppDelegate.swift 中添加 RxSwift 的引用，然后在 AppDelegate 类中添加 DisposeBag 类型的实例。
import RxSwift
class AppDelegate {
// ...
let disposeBag = DisposeBag()
// ...
}
在 AppDelegate 类的 applicationDidFinishLaunching 方法中添加以下代码
Post.getPostAsString().do(onNext: { print($0) }).subscribe().disposed(by: disposeBag)
Post.getPostAsJson().do(onNext: { print($0.description) }).subscribe().disposed(by: disposeBag)
Post.getPosts(n: 2).do(onNext: { print($0.description) }).subscribe().disposed(by: disposeBag)
Post.createPost().do(onNext: { print($0) }).subscribe().disposed(by: disposeBag)
Post.updatePost().do(onNext: { print($0) }).subscribe().disposed(by: disposeBag)
Post.deletePost().do(onNext: { print($0) }).subscribe().disposed(by: disposeBag)
输出结果
{
"userId": 1,
"id": 1,
"title": "sunt aut facere repellat provident occaecati excepturi optio reprehenderit",
"body": "quia et suscipit\nsuscipit recusandae consequuntur expedita et cum\nreprehenderit molestiae ut ut quas totam\nnostrum rerum est autem sunt rem eveniet architecto"
}
Post {userId = 1, id = 1, title = "sunt aut facere repellat provident occaecati excepturi optio reprehenderit", body = "quia et suscipit\nsuscipit recusandae consequuntur expedita et cum\nreprehenderit molestiae ut ut quas totam\nnostrum rerum est autem sunt rem eveniet architecto"}
Post {userId = 1, id = 2, title = "qui est esse", body = "est rerum tempore vitae\nsequi sint nihil reprehenderit dolor beatae ea dolores neque\nfugiat blanditiis voluptate porro vel nihil molestiae ut reiciendis\nqui aperiam non debitis possimus qui neque nisi nulla"}
Post {userId = 1, id = 1, title = "sunt aut facere repellat provident occaecati excepturi optio reprehenderit", body = "quia et suscipit\nsuscipit recusandae consequuntur expedita et cum\nreprehenderit molestiae ut ut quas totam\nnostrum rerum est autem sunt rem eveniet architecto"}
{}
{
"{\"body\":\"test body\",\"id\":0,\"title\":\"test title\",\"userId\":101}": "",
"id": 101
}
{
"id": 1
}
