URLRequest相等不包括httpBody

Question

概观

有2个URLRequests，一个有httpBody，另一个没有httpBody。 然而，相比之下，它表明两者是相等的。

题

这是预期的行为还是我错过了什么？

码

let url = URL(string: "www.somevalidURL.com")!

var r1 = URLRequest(url: url)
r1.addValue("Content-Type", forHTTPHeaderField: "application/json; charset=utf-8")
r1.httpBody = makeBody(withParameters: ["email" : "[email protected]"])

var r2 = URLRequest(url: url)
r2.addValue("Content-Type", forHTTPHeaderField: "application/json; charset=utf-8")

if r1 == r2 {
    print("requests are equal")
}
else {
    print("requests are not equal")
}

if r1.httpBody == r2.httpBody {
    print("body is equal")
}
else {
    print("body is not equal")
}

func makeBody(withParameters bodyParameters: [String : Any]?) -> Data? {
    guard let bodyParameters = bodyParameters,
        !bodyParameters.isEmpty else {
            return nil
    }
    let body : Data?
    do {
        body = try JSONSerialization.data(withJSONObject: bodyParameters,
                                          options: .prettyPrinted)
    }
    catch {
        print("Error in creating Web Service Body = \(error)")
        body = nil
    }
    return body
}

产量

requests are equal
body is not equal

---

Xcode 10 Swift版本：4.2

Answer 1

URLRequest是基础类型NSURLRequest的Swift叠加类型，因此==最终称为isEqual()的NSURLRequest方法。

Foundation库是非Apple平台的开源软件，在NSURLRequest.swift#L245，我们发现：

open override func isEqual(_ object: Any?) -> Bool {
    //On macOS this fields do not determine the result:
    //allHTTPHeaderFields
    //timeoutInterval
    //httBody
    //networkServiceType
    //httpShouldUsePipelining
    guard let other = object as? NSURLRequest else { return false }
    return other === self
        || (other.url == self.url
            && other.mainDocumentURL == self.mainDocumentURL
            && other.httpMethod == self.httpMethod
            && other.cachePolicy == self.cachePolicy
            && other.httpBodyStream == self.httpBodyStream
            && other.allowsCellularAccess == self.allowsCellularAccess
            && other.httpShouldHandleCookies == self.httpShouldHandleCookies)

所以这似乎是故意的。

Answer 2

如果你来到这里想知道为什么你的相同URLRequests不像我一样彼此相同我发现了URLRequest的等同实现的区别在于httpBody被设置为nil或者默认为nil。

如果我们执行以下操作：

let request = URLRequest(url: URL(string: "test.com"))
var expectedRequest = URLRequest(url: URL(string: "test.com"))
expectedRequest.httpBody = nil

然后：

request == expectedRequest //false
print(request.httpBody) // nil
request.httpBody = nil
request == expectedRequest //true

明确地将httpBody设置为nil将解决此问题。事实上，身体是什么并不重要，只是它已被明确设定。

request.httpBody = Data()
request == expectedRequest //true

---

可能的解释

正如马丁正确地指出Swift's source code不包括httpBody。但是，所有属性（在链接中）相等（并且都可以作为NSURLRequests进行转换）不会返回true（请参阅下面的lldb输出）。我只能假设链接代码被覆盖以包含另一个属性，并且当在didSet willSet上调用httpBody或时这会被修改