iOS：如何转换字符串数据？

Question

我有向正文添加值的代码：

let body = NSMutableData()
let mimetype = "image/jpg"

//define the data post parameter

body.append("--\(boundary)\r\n".data(using: String.Encoding.utf8)!)
body.append("Content-Disposition:form-data; name=\"eventId\"\r\n\r\n".data(using: String.Encoding.utf8)!)
body.append("\(eventId)\r\n".data(using: String.Encoding.utf8)!)

body.append("--\(boundary)\r\n".data(using: String.Encoding.utf8)!)
body.append("Content-Disposition:form-data; name=\"contactId\"\r\n\r\n".data(using: String.Encoding.utf8)!)
body.append("\(contactId)\r\n".data(using: String.Encoding.utf8)!)

body.append("--\(boundary)\r\n".data(using: String.Encoding.utf8)!)
body.append("Content-Disposition:form-data; name=\"type\"\r\n\r\n".data(using: String.Encoding.utf8)!)
body.append("\(type)\r\n".data(using: String.Encoding.utf8)!)

body.append("--\(boundary)\r\n".data(using: String.Encoding.utf8)!)
body.append("Content-Disposition:form-data; name=\"file\"; filename=\"\(fileName)\"\r\n".data(using: String.Encoding.utf8)!)
body.append("Content-Type: \(mimetype)\r\n\r\n".data(using: String.Encoding.utf8)!)
body.append(image_data!)
body.append("\r\n".data(using: String.Encoding.utf8)!)

body.append("--\(boundary)--\r\n".data(using: String.Encoding.utf8)!)

request.httpBody = body as Data

如何将其转换为字符串？我想获得界限，但不可能做到。

[当我这样做时，它使我为零：let test = String(data: body as Data, encoding: .utf8)

非常感谢。

Answer 1

如果需要边界，则应在与图像数据不同的对象中创建其页眉和页脚数据：

var body = Data()
let boundary = UUID().uuidString
let eventId = "your event ID"
let contactId = "your contact ID"
let type = "your type string"
let mimetype = "image/jpg"
let fileName = "the file name"
let imageData = Data() // your image data
let boundaryHeader = Data("""
--\(boundary)\r\n
Content-Disposition:form-data; name=\"eventId\"\r\n\r\n
\(eventId)\r\n
--\(boundary)\r\n
Content-Disposition:form-data; name=\"contactId\"\r\n\r\n
\(contactId)\r\n
--\(boundary)\r\n
Content-Disposition:form-data; name=\"type\"\r\n\r\n
\(type)\r\n
--\(boundary)\r\n
Content-Disposition:form-data; name=\"file\"; filename=\"\(fileName)\"\r\n
Content-Type: \(mimetype)\r\n\r\n
""".utf8)

let boundaryFooter = Data("""
\r\n
--\(boundary)--\r\n
""".utf8)

body.append(boundaryHeader)
body.append(imageData)
body.append(boundaryFooter)

var request = URLRequest(url: URL(string: "http://www.example.com/whatever")!)
request.httpBody = body

print(String(data: boundaryHeader, encoding: .utf8) ?? "nil")

---

这将打印：

Content-Disposition：form-data; name =“ contactId”

您的联系人ID

-2583374D-68AF-4EE1-96A5-740CCA17C51D

Content-Disposition：form-data; name =“ type”

您的类型字符串

-2583374D-68AF-4EE1-96A5-740CCA17C51D

Content-Disposition：form-data; name =“文件”; filename =“文件名”

内容类型：图像/ jpg