Alamofire从基础到进阶 基础请求与响应（一）

Alamofire
Version：4.5.1
Swift Version: 4.0.3

Podfiles

# Uncomment the next line to define a global platform for your proje
platform :ios, '8.0'
target 'UseageAlamofire' do
  use_frameworks!
  pod 'Alamofire'
end

目录：
Alamofire从基础到进阶 基础请求与响应（一）
Alamofire从基础到进阶 小技巧（二）

创建一个简单的Request

let request = Alamofire.request("http://httpbin.org/ip")
print("request = \(request)")
输出：request = GET http://httpbin.org/ip

上面的 GET 是请求类型，后面紧跟的就是你的请求的地址，还有另外两种创建一个Request的方式：

• request(_ urlRequest: ）
• request(_ url:, method:, parameters:, encoding:, headers: )
  我们使用一下看看效果：

let urlRequest = URLRequest(url: URL(string: "http://httpbin.org/ip")!)
let request2 = Alamofire.request(urlRequest)
print("request2 = \(request2)")
输出：request2 = GET http://httpbin.org/ip

let url = "http://httpbin.org/ip"
let method: HTTPMethod = .get
let parameters: Parameters = ["name": "chao"]
let encoding: URLEncoding = .default
let headers: HTTPHeaders = ["Content-Type": "application/json"]
let request3 = Alamofire.request(url, method: method, parameters: parameters, encoding: encoding, headers: headers)
print("request3 = \(request3)")
输出：request3 = GET http://httpbin.org/ip?name=chao

使用一下Response响应

我们已经学会了用Alamofire创建一个Request，我们最终想要的是从服务器拿到数据，我们可以这样写：

let url2 = "http://httpbin.org/ip"
Alamofire.request(url2).response(completionHandler: { defaultResponse in
    print("request = ", defaultResponse.request)
    print("-----------------------------------")
    print("response = ", defaultResponse.response)
    print("-----------------------------------")
    print("data = ", defaultResponse.data)
    print("-----------------------------------")
    print("error = ", defaultResponse.error)
    print("-----------------------------------")
    print("metrics = ", defaultResponse.metrics)
    print("-----------------------------------")
    print("timeline = ", defaultResponse.timeline)
})

输出：

response =  Optional( { URL: http://httpbin.org/ip } { Status Code: 200, Headers {
    "Access-Control-Allow-Credentials" =     (
        true
    );
    "Access-Control-Allow-Origin" =     (
        "*"
    );
    Connection =     (
        "keep-alive"
    );
    "Content-Length" =     (
        32
    );
    "Content-Type" =     (
        "application/json"
    );
    Date =     (
        "Fri, 30 Mar 2018 10:41:03 GMT"
    );
    Server =     (
        "meinheld/0.6.1"
    );
    Via =     (
        "1.1 vegur"
    );
    "X-Powered-By" =     (
        Flask
    );
    "X-Processed-Time" =     (
        0
    );
} })
-----------------------------------
data =  Optional(32 bytes)
-----------------------------------
error =  nil
-----------------------------------
metrics =  Optional((Task Interval) <_NSConcreteDateInterval: 0x600000030e40> (Start Date) 2018-03-30 10:41:03 +0000 + (Duration) 0.677700 seconds = (End Date) 2018-03-30 10:41:03 +0000
(Redirect Count) 0
(Transaction Metrics) (Request)  { URL: http://httpbin.org/ip }
(Response)  { URL: http://httpbin.org/ip } { Status Code: 200, Headers {
    "Access-Control-Allow-Credentials" =     (
        true
    );
    "Access-Control-Allow-Origin" =     (
        "*"
    );
    Connection =     (
        "keep-alive"
    );
    "Content-Length" =     (
        32
    );
    "Content-Type" =     (
        "application/json"
    );
    Date =     (
        "Fri, 30 Mar 2018 10:32:49 GMT"
    );
    Server =     (
        "meinheld/0.6.1"
    );
    Via =     (
        "1.1 vegur"
    );
    "X-Powered-By" =     (
        Flask
    );
    "X-Processed-Time" =     (
        0
    );
} }
(Fetch Start) 2018-03-30 10:41:03 +0000
(Domain Lookup Start) (null)
(Domain Lookup End) (null)
(Connect Start) (null)
(Secure Connection Start) (null)
(Secure Connection End) (null)
(Connect End) (null)
(Request Start) 2018-03-30 10:41:03 +0000
(Request End) 2018-03-30 10:41:03 +0000
(Response Start) 2018-03-30 10:41:03 +0000
(Response End) 2018-03-30 10:41:03 +0000
(Protocol Name) (null)
(Proxy Connection) NO
(Reused Connection) YES
(Fetch Type) Local Cache

(Request)  { URL: http://httpbin.org/ip }
(Response)  { URL: http://httpbin.org/ip } { Status Code: 200, Headers {
    "Access-Control-Allow-Credentials" =     (
        true
    );
    "Access-Control-Allow-Origin" =     (
        "*"
    );
    Connection =     (
        "keep-alive"
    );
    "Content-Length" =     (
        32
    );
    "Content-Type" =     (
        "application/json"
    );
    Date =     (
        "Fri, 30 Mar 2018 10:41:03 GMT"
    );
    Server =     (
        "meinheld/0.6.1"
    );
    Via =     (
        "1.1 vegur"
    );
    "X-Powered-By" =     (
        Flask
    );
    "X-Processed-Time" =     (
        0
    );
} }
(Fetch Start) 2018-03-30 10:41:03 +0000
(Domain Lookup Start) 2018-03-30 10:41:03 +0000
(Domain Lookup End) 2018-03-30 10:41:03 +0000
(Connect Start) 2018-03-30 10:41:03 +0000
(Secure Connection Start) (null)
(Secure Connection End) (null)
(Connect End) 2018-03-30 10:41:03 +0000
(Request Start) 2018-03-30 10:41:03 +0000
(Request End) 2018-03-30 10:41:03 +0000
(Response Start) 2018-03-30 10:41:03 +0000
(Response End) 2018-03-30 10:41:03 +0000
(Protocol Name) http/1.1
(Proxy Connection) NO
(Reused Connection) NO
(Fetch Type) Network Load

)
-----------------------------------
timeline =  Timeline: { "Latency": 0.677 secs, "Request Duration": 0.678 secs, "Serialization Duration": 0.000 secs, "Total Duration": 0.678 secs }

上面输出了很多很多的东西，我们来具体看看都有什么?
DefaultDataResponse
这个响应结果是Alamofire提供的一个结构体，我们看一下源码：

/// The URL request sent to the server.
public let request: URLRequest?

/// The server's response to the URL request.
public let response: HTTPURLResponse?

/// The data returned by the server.
public let data: Data?

/// The error encountered while executing or validating the request.
public let error: Error?

/// The timeline of the complete lifecycle of the request.
public let timeline: Timeline

var _metrics: AnyObject?

DefaultDataResponse结构体定义了上面这几个属性：
reqeuest就是你定义的请求
reponse是响应结果
data是服务器返回给我们的数据
error是执行请求和验证结果时候的错误
timeline是该请求从请求到收到结果的一条时间线
_metrics是iOS10及以后提供的一个时间线的属性，和timeline大同小异，所以你要使用的话必须是支持iOS10以后的版本才能使用

/// 这样写就没有问题了
if #available(iOS 10, *) {
    print("metrics = ", defaultResponse.metrics)
}

不过除了response响应处理以外我们还有4种其他的响应处理方式：

• responseJSON
• reponseData
• responseString
• responsePropertyList

在我们的程序里，大多数用到的是第一和第二种。
responseString响应处理的是字符串
responsePropertyList响应处理的是plist(类似于responseJSON)都是转换成Any类型。
responseJSON是将服务器返回数据序列化为json然后转换成Any.
reponseData是将服务器返回数据序列化为Data然后转换成Data.

Alamofire强烈建议我们使用这四种去做处理，不建议我们使用DefaultResponse，这个就不纠结了我们用下面四种已经足够了。

先看responseData:

Alamofire.request(url2).responseData(completionHandler: { response in
    print(response.result.value)
})
输出：Optional(32 bytes)

我们看到了reponse.result，这个result是啥？我们点进去看看

enum Result {
    case success(Value)
    case failure(Error)

    public var value: Value? {
        switch self {
        case .success(let value):
            return value
        case .failure:
            return nil
        }
    }
}
/// 源码我没有展示完 我们只看关于这篇文章的

Reust是一个泛型的枚举，当我们使用responseData的使用，Value就会被转换为Data，当我们调用response.result.vlaue的时候就会看到输出了"Optional(32 bytes)"这很明显是Data类型,然后我们把它解析出来看看是什么:

let url2 = "http://httpbin.org/ip"
Alamofire.request(url2).responseData(completionHandler: { response in
    guard let value = response.result.value else { return }
    let result = try? JSONSerialization.jsonObject(with: value, options: [])
    guard let res = result else { return }
    let dictionary = res as! [String: Any]
    print("dictionary = ", dictionary)
})
输出：dictionary =  ["origin": 101.81.57.239]

这就是responseData的简单用法了.
下面我们来看responseJSON怎么使用：

Alamofire.request(url2).responseJSON { response in
     print(response.result.value)
}
输出： Optional({ origin = "101.81.57.239";})

很明显它是一个JSON格式，这就是Alamofire序列化为JSON的好处。为什么我们使用Reulst，因为它是Alamofire序列化好服务器给我们使用的一个属性，所以我们不用再去做序列化的操作，直接使用就好了。下面我们转化成字典类型:

Alamofire.request(url2).responseJSON { response in
    guard let value = response.result.value else { return }
    let dictionary = value as! [String: Any]
    print("dictionary = ", dictionary)
}
输出：dictionary =  ["origin": 101.81.57.239]

和responseData是一样的输出结果，但是比responseData要少两步, 所以如果你的程序后台返回的是JSON格式的数据，你直接使用responseJSON要比responseData要方便很多。

--以此来记录 Usage Alamofire ^ _^ --