URLRequest 相等性不包括 httpBody

Question

概览

有2个URLRequest，一个有httpBody，一个没有httpBody。
然而，当比较时，它表明两者是相等的。

问题

这是预期的行为还是我遗漏了什么？

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

Swift版本：4.2}

Answer 1

URLRequest是Foundation类型NSURLRequest的Swift覆盖类型，这样==最终调用的isEqual()方法 NSURLRequest.

Foundation 库是针对非 Apple 平台的开源，并且在 NSURLRequest.swift#L252 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相同的 URLRequest 不像我一样彼此不相等，我发现原因是 URLRequest equatable 实现区分 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。事实上 body 是什么并不重要，重要的是它已经明确设置了。

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

可能的解释

正如 Martin 正确指出的那样 Swift's source code 不包括 httpBody。但是，所有属性（在 link 中）都是相等的（并且都可以作为 NSURLRequests 进行转换）不会 return true（请参阅下面的 lldb 输出）。我只能假定 linked 代码被覆盖以包含另一个属性并且当 didSet 或 willSet 在 httpBody 上调用时会修改此代码

URLRequest 相等性不包括 httpBody

URLRequest equality doesn't include httpBody

swift

urlrequest

swift4.2

概览

问题

代码

输出