ios - Swift - 将二进制文件发送到服务器(转换为字符串请求)

Question

这是我构建一个发送到服务器的请求的函数。当它是一个小的纯文本文件时，这段代码工作得很好。但是，当我向它传递一个二进制文件时，它会在下面指示的行上崩溃(当它试图将其转换为 utf 字符串并炸毁 b/c 时，转换不起作用，因为它创建了一个 nil 值):

func buildFilePushRequest(fromUrl url: URL, httpBody: Data? = nil, fileName: String) -> NSMutableURLRequest? {
    let cachePolicy = NSURLRequest.CachePolicy.reloadIgnoringLocalCacheData
    let request = NSMutableURLRequest(url: url, cachePolicy: cachePolicy, timeoutInterval: 2.0)
    request.httpMethod = "POST"

    // Set Content-Type in HTTP header.
    let boundaryConstant = "Boundary-7MA4YWxkTLLu0UIW"; // This should be auto-generated.
    let contentType = "multipart/form-data; boundary=" + boundaryConstant

    let fileName = fileName

    request.setValue(contentType, forHTTPHeaderField: "Content-Type")
    request.setValue("keep-alive", forHTTPHeaderField: "Connection")

    var dataString = "--\(boundaryConstant)\r\n"
    dataString += "Content-Disposition: form-data; name=file; filename=\"\(fileName)\"\r\n"
    dataString += "Content-Type: octet-stream\r\n\r\n"
    dataString += String(data: httpBody!, encoding: .utf8)! <-- CRASHES HERE
    dataString += "\r\n"
    dataString += "--\(boundaryConstant)--\r\n"

    print("dataString: \(dataString)")

    let requestBodyData = dataString.data(using: .utf8)
    request.httpBody = requestBodyData

    return request
}

我读过一点，对于二进制类型数据，base64 比 utf8 更好，但我不确定如何最好地修改上面的代码来使用它，或者是否有更好的解决方案？提前致谢!

Answer 1

如果 httpBody 参数可以包含二进制数据，您可以将整个 http 正文复合为 Data

首先请使用原生的URLRequest，它是可变的variable，为什么返回值是可选的？

func buildFilePushRequest(fromUrl url: URL, httpBody: Data? = nil, fileName: String) -> URLRequest {
    var request = URLRequest(url: url, cachePolicy: .reloadIgnoringLocalCacheData, timeoutInterval: 2.0)

...

var data = Data("--\(boundaryConstant)\r\n".utf8)
data += Data("Content-Disposition: form-data; name=file; filename=\"\(fileName)\"\r\n".utf8)
data += Data("Content-Type: octet-stream\r\n\r\n".utf8)
if let body = httpBody { data += body }
data += Data("\r\n".utf8)
data += Data("--\(boundaryConstant)--\r\n".utf8)

request.httpBody = data