iOS swift NSMutableData没有成员appendString [英] iOS swift NSMutableData has no member appendString

问题描述

你好，我是Swift的新手，我正在学习一个教程并创建相同的代码以上传图片.我现在使用的是swift 3，看来 NSMutableData()不再具有 appendString 方法可用，我该怎么做?我正在关注的教程在这里 http://swiftdeveloperblog.com/image-upload-example/而我的代码就是这个

Hello I am new to swift and I am following a tutorial and creating the same code in order to Upload an image . I am now using swift 3 and it seems like NSMutableData() no longer has the appendString method available what can I do as a substitute ? The tutorial I am following is here http://swiftdeveloperblog.com/image-upload-example/ and my code is this

func createBodyWithParameters(parameters: [String: String]?, filePathKey: String?, imageDataKey: NSData, boundary: String) -> NSData {
       let body = NSMutableData()

        if parameters != nil {
            for (key, value) in parameters! {
                body.("--\(boundary)\r\n")
                body.appendString("Content-Disposition: form-data; name=\"\(key)\"\r\n\r\n")
                body.appendString("\(value)\r\n")
            }
        }

        let filename = "user-profile.jpg"
        let mimetype = "image/jpg"

        body.appendString(options: <#T##NSData.Base64EncodingOptions#>)("--\(boundary)\r\n")
        body.appendString("Content-Disposition: form-data; name=\"\(filePathKey!)\"; filename=\"\(filename)\"\r\n")
        body.appendString("Content-Type: \(mimetype)\r\n\r\n")
        body.appendString("\r\n")



        body.appendString("--\(boundary)--\r\n")

        return body
    }

再次出现问题是 appendString ，因为我收到了错误消息:

Again the issue is with the appendString as I am getting the error:

值没有成员appendString

我一直在寻找解决方法，但没有找到任何解决方法，并且我有可用的 append 方法，但是它没有String.

I been searching for work arounds but have not found any and I have the append method available but it does not take a String.

推荐答案

正如@dan在评论中指出的那样，该方法是您正在查看的教程的一部分.不过，在Swift中无需定义自定义方法就足够了.

As @dan points out in the comments, that method is part of the tutorial you’re looking at. It’s easy enough in Swift without defining a custom method, though.

首先，不要使用NSMutableData；而是使用新的Data结构，该结构是可变的还是不可变的，具体取决于您使用的是var还是let:

First, don’t use NSMutableData; instead, use the new Data struct, which will be either mutable or immutable depending on whether you use var or let:

var body = Data()

然后追加UTF-8字节:

Then to append UTF-8 bytes:

body.append(Data("foo".utf8))

(如果您需要使用UTF-8以外的其他编码，还有其他String种方法用于其他编码.)

(There are other String methods for other encodings if you need something other than UTF-8.)

如果您想了解本教程的确切行为，请按照以下方法将其方法转换为Swift 3:

If you want the exact behavior of the tutorial, here’s how to translate its method to Swift 3:

extension Data {
  mutating func append(string: String) {
    let data = string.data(
        using: String.Encoding.utf8,
        allowLossyConversion: true)
    append(data!)
  }
}

…

body.append("foo")

不过，出于两个原因，我不建议您使用此代码.首先，有损转换意味着您的应用可能会静默丢弃重要数据.其次，强制解包(data!而不是data)意味着在编码出现问题时，您的应用将崩溃，而不显示有用的错误.

I wouldn’t recommend this code, though, for two reasons. First, the lossy conversion means that your app may silently discard important data. Second, the force unwrap (data! instead of data) means that in case of encoding trouble, your app will crash instead of displaying a useful error.

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