Merge pull request Moya#1343 from pietrocaselani/UpdateParameterEncod…

…ingExample

Add custom parameter encoding example.

docs/Examples/ParameterEncoding.md

@@ -0,0 +1,42 @@
+# Use a custom ParameterEncoding
+Moya is using dictionary as a root container for JSON data. But sometimes you will need to send JSON array as a root element instead. Here is solution by writing your own parameter encoding:
+
+Define a struct or class:
+```swift
+import Alamofire
+
+struct JSONArrayEncoding: ParameterEncoding {
+    static let `default` = JSONArrayEncoding()
+
+    func encode(_ urlRequest: URLRequestConvertible, with parameters: Parameters?) throws -> URLRequest {
+        var request = try urlRequest.asURLRequest()
+
+        guard let json = parameters?["jsonArray"] else {
+            return request
+        }
+
+        let data = try JSONSerialization.data(withJSONObject: json, options: [])
+
+        if request.value(forHTTPHeaderField: "Content-Type") == nil {
+            request.setValue("application/json", forHTTPHeaderField: "Content-Type")
+        }
+
+        request.httpBody = data
+
+        return request
+    }
+}
+```
+
+Configure the target:
+
+```swift
+public var task: Task {
+    switch self {
+    case .api:
+        return .requestParameters(parameters: ["jsonArray": ["Yes", "What", "abc"]], encoding: JSONArrayEncoding.default)
+    }
+}
+```
+
+This will send data as a JSON array `["Yes", "What", "Abc"]` for the `.api` endpoint. For more information, see discussion in: [#467](https://github.com/Moya/Moya/issues/467)