在使用 Moya 的过程中，会遇到这种情况：url 当中需要动态设置参数，body 中也要设置参数。
比如请求的 URL 当中需要添加 userID ，在 body 当中需要传入一个 JSON 格式的参数 {"roomID": "123"} 。
url 和 body 同时提交
方案一（失败）
在 path 方法中拼接 url 的参数，在 task 中提交 body 的参数。
public enum LiveShowRequest {
case anchorHeartBeat(userID: String,
roomID: String)
}
extension LiveShowRequest: TargetType {
public var path: String {
switch self {
case .anchorHeartBeat(let userID, _):
return "anchor_heartbeat?userID=\(userID)"
}
}
public var task: Task {
switch self {
case let .anchorHeartBeat(_, roomID):
var params = ["roomID": roomID] as [String : Any]
return .requestParameters(parameters: params, encoding: JSONEncoding.default)
}
}
}
经过测试，这样是不行的，因为 Moya 会对 path 的返回值进行编码，导致用于拼接参数的 ? 被编码成了 %3f ，服务器无法解析参数了。
方案二（成功）
在 task 中使用 requestCompositeParameters ，可以同时设置 bodyParameters 和 urlParameters 。
extension LiveShowRequest: TargetType {
public var path: String {
switch self {
case .anchorHeartBeat(let userID, _):
return "anchor_heartbeat"
}
}
public var task: Task {
switch self {
case let .anchorHeartBeat(userID, roomID):
var params = ["roomID": roomID] as [String : Any]
var urlParameters = ["userID": userID]
return .requestCompositeParameters(bodyParameters: params,
bodyEncoding: JSONEncoding.default,
urlParameters: urlParameters)
}
}
}
这种方式可以处理同时传入 url 和 body 参数的情况。
方法三（成功）
在 baseURL 中拼接 url 参数，在 task 中设置 body 参数，可以避免方法一中 ? 被编码的问题。
extension LiveShowRequest: TargetType {
public var baseURL: URL {
switch self {
case let .anchorHeartBeat(userID, _):
return URL(string: BaseURL + "?userID=\(userID)")!
}
}
public var path: String {
switch self {
case .anchorHeartBeat:
return "anchor_heartbeat"
}
}
public var task: Task {
switch self {
case let .anchorHeartBeat(_, roomID):
var params = ["roomID": roomID] as [String : Any]
return .requestParameters(parameters: params, encoding: JSONEncoding.default)
}
}
url 参数的编码问题
假如传入的 url 参数当中有 * ，比如上面的例子当中的 userID 为 0558eba*1400489990 ，Moya 会将 * 转换为 %2A ，也就是进行了 url 编码。但是 * 本身不需要进行 url 编码，Moay 为什么要对 * 进行编码呢？
在 Moya 当中，url 的参数是通过 URLEncoding 进行编码的。
public struct URLEncoding: ParameterEncoding {
/// Returns a percent-escaped string following RFC 3986 for a query string key or value.
///
/// RFC 3986 states that the following characters are "reserved" characters.
///
/// - General Delimiters: ":", "#", "[", "]", "@", "?", "/"
/// - Sub-Delimiters: "!", "$", "&", "'", "(", ")", "*", "+", ",", ";", "="
///
/// In RFC 3986 - Section 3.4, it states that the "?" and "/" characters should not be escaped to allow
/// query strings to include a URL. Therefore, all "reserved" characters with the exception of "?" and "/"
/// should be percent-escaped in the query string.
///
/// - parameter string: The string to be percent-escaped.
///
/// - returns: The percent-escaped string.
public func escape(_ string: String) -> String {
let generalDelimitersToEncode = ":#[]@" // does not include "?" or "/" due to RFC 3986 - Section 3.4
let subDelimitersToEncode = "!$&'()*+,;="
var allowedCharacterSet = CharacterSet.urlQueryAllowed
allowedCharacterSet.remove(charactersIn: "\(generalDelimitersToEncode)\(subDelimitersToEncode)")
var escaped = ""
//==========================================================================================================
//
// Batching is required for escaping due to an internal bug in iOS 8.1 and 8.2. Encoding more than a few
// hundred Chinese characters causes various malloc error crashes. To avoid this issue until iOS 8 is no
// longer supported, batching MUST be used for encoding. This introduces roughly a 20% overhead. For more
// info, please refer to:
//
// - https://github.com/Alamofire/Alamofire/issues/206
//
//==========================================================================================================
if #available(iOS 8.3, *) {
escaped = string.addingPercentEncoding(withAllowedCharacters: allowedCharacterSet) ?? string
} else {
let batchSize = 50
var index = string.startIndex
while index != string.endIndex {
let startIndex = index
let endIndex = string.index(index, offsetBy: batchSize, limitedBy: string.endIndex) ?? string.endIndex
let range = startIndex..<endIndex
let substring = string[range]
escaped += substring.addingPercentEncoding(withAllowedCharacters: allowedCharacterSet) ?? String(substring)
index = endIndex
}
}
return escaped
}
}
拼接进 URL 的参数的 key 和 value，都会调用 escape 方法进行编码。escape 方法根据 RFC 3986 返回百分号转移的字符串。在调用 addingPercentEncoding 之前，先移除了 CharacterSet.urlQueryAllowed 中包含在 generalDelimitersToEncode 和 subDelimitersToEncode 中的字符。
let generalDelimitersToEncode = ":#[]@" // does not include "?" or "/" due to RFC 3986 - Section 3.4
let subDelimitersToEncode = "!$&'()*+,;="
var allowedCharacterSet = CharacterSet.urlQueryAllowed
allowedCharacterSet.remove(charactersIn: "\(generalDelimitersToEncode)\(subDelimitersToEncode)")
可以通过下面的扩展方法查看包含在 CharacterSet.urlQueryAllowed 的字符串。（方法来自 stackoverflow）
extension CharacterSet {
func characters() -> [Character] {
// A Unicode scalar is any Unicode code point in the range U+0000 to U+D7FF inclusive or U+E000 to U+10FFFF inclusive.
return codePoints().compactMap { UnicodeScalar($0) }.map { Character($0) }
}
func codePoints() -> [Int] {
var result: [Int] = []
var plane = 0
// following documentation at https://developer.apple.com/documentation/foundation/nscharacterset/1417719-bitmaprepresentation
for (i, w) in bitmapRepresentation.enumerated() {
let k = i % 0x2001
if k == 0x2000 {
// plane index byte
plane = Int(w) << 13
continue
}
let base = (plane + k) << 3
for j in 0 ..< 8 where w & 1 << j != 0 {
result.append(base + j)
}
}
return result
}
}
// 使用方法
var allowedCharacterSet = CharacterSet.urlQueryAllowed
debugPrint(allowedCharacterSet.characters())
// 结果
["!", "$", "&", "\'", "(", ")", "*", "+", ",", "-", ".", "/", "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", ":", ";", "=", "?", "@", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "_", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "~"]
如果，恰好 url 参数中有这些字符，又不想被编码，要怎么处理呢？只能自定义一个符合 ParameterEncoding 的类型，实现自定义编码方式。
下面的 MultipleEncoding 由 https://github.com/Moya/Moya/issues/1059 提供的思路实现。初始化 MultipleEncoding 时，通过 urlParameters 定义需要被 url 编码的 key，其他的 key 则为编码为 body。
struct MultipleEncoding : ParameterEncoding {
var urlParameters: [String]?
init(urlParameters:[String]?) {
self.urlParameters = urlParameters
}
func encode(_ urlRequest: Alamofire.URLRequestConvertible, with parameters: Parameters?) throws -> URLRequest {
guard let parameters = parameters else { return urlRequest as! URLRequest }
var urlParams: [String: Any] = [:]
var jsonParams: [String: Any] = [:]
parameters.forEach { (key: String, value: Any) in
if urlParameters?.contains(key) ?? false {
urlParams[key] = value
} else {
jsonParams[key] = value
}
}
// Encode URL Params
// 过程和 URLEncoding.queryString.encode(urlRequest, with: urlParams) 一致
var urlRequest = try urlRequest.asURLRequest()
if let url = urlRequest.url {
if var urlComponents = URLComponents(url: url, resolvingAgainstBaseURL: false), !urlParams.isEmpty {
let percentEncodedQuery = (urlComponents.percentEncodedQuery.map { $0 + "&" } ?? "") + query(urlParams)
urlComponents.percentEncodedQuery = percentEncodedQuery
urlRequest.url = urlComponents.url
}
}
//Encode JSON
return try JSONEncoding.default.encode(urlRequest, with: jsonParams)
}
private func query(_ parameters: [String: Any]) -> String {
// 直接复制 URLEncoding 中的方法
}
public func queryComponents(fromKey key: String, value: Any) -> [(String, String)] {
// 直接复制 URLEncoding 中的方法
}
// escape 只需要根据需要移出不希望被编码的字符
public func escape(_ string: String) -> String {
let generalDelimitersToEncode = ":#[]@" // does not include "?" or "/" due to RFC 3986 - Section 3.4
let subDelimitersToEncode = "!$&'()*+,;="
var allowedCharacterSet = CharacterSet.urlQueryAllowed
// allowedCharacterSet.remove(charactersIn: "\(generalDelimitersToEncode)\(subDelimitersToEncode)")
// 下面的代码和 URLEncoding 中的方法一致
}
}
使用时如下。
extension LiveShowRequest: TargetType {
public var path: String {
switch self {
case .anchorHeartBeat(let userID, _):
return "anchor_heartbeat"
}
}
public var task: Task {
switch self {
case let .anchorHeartBeat(userID, roomID):
var params = ["roomID": roomID,
"userID": userID,
] as [String : Any]
let urlParameters = ["userID"]
return .requestParameters(parameters: params, encoding: MultipleEncoding(urlParameters: urlParameters))
}
}
}
这样就自定了 url 和 body 编码的整个过程。
