URLRequest相等不包含httpBody

Question

概述

有2个URLRequest，一个带有httpBody，另一个没有httpBody。
但是，进行比较时，表明两者相等。

问题

这是预期的行为还是我错过了什么？

代码

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" : "a@b.com"])

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
}

输出

requests are equal
body is not equal

---

_{Xcode 10
迅捷版：4.2}

Answer 1

URLRequest是Foundation类型NSURLRequest的Swift覆盖类型，因此==最终调用了isEqual()方法 NSURLRequest。

Foundation库是非Apple平台的开源软件，位于 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

如果您来这里想知道为什么您的相同URLRequest彼此不相等，就像我一样，我发现原因是 URLRequest的等价实现区分了httpBody设置为nil或默认为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

将httpBody显式设置为nil将解决此问题。实际上，主体是什么都没有关系，只是它已被明确设置。

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

---

可能的解释

正如马丁正确指出的那样，Swift's source code不包含httpBody。但是，所有（在链接中）相等的属性（都可以作为NSURLRequests强制转换）不会返回true（请参见下面的lldb输出）。我只能假定链接的代码被重写为包括另一个属性，并且在didSet上调用willSet或httpBody时会对此属性进行修改