iOS swift NSMutableData has no member appendString

Question

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
    }

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

value of type NSMutableData has no member appendString

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.

`NSMutableData` has never had an `appendString` method, the tutorial you are looking at adds that method in an extension at the bottom of their source code. — dan, Dec 16 '16 at 18:37

Paul Cantrell · Accepted Answer · 2016-12-16T18:53:33.437

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.

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()

Then to append UTF-8 bytes:

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

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

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")

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.

Don't force unwrap your data `extension Data { mutating func append(string: String) { guard let data = string.data( using: .utf8, allowLossyConversion: true) else { return } append(data) } }` — Leo Dabus, Dec 16 '16 at 20:23
@Leo: silently ignoring the error is possibly even _worse_ than crashing. The correct approach depends on the situation: if the string isn't encodable, is it better to (1) do nothing and let the app proceed thinking that the append succeeded, (2) stop everything because the error never should have happened, or (3) take some recovery action, such as displaying an error to the user? — Paul Cantrell, Feb 09 '17 at 03:11

score 5 · Answer 2 · edited Mar 23 '17 at 06:57

5

extension NSMutableData {

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

This work With Me Swift 3

edited Mar 23 '17 at 06:57

neer

4,031
6
20
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answered Mar 23 '17 at 06:45

Abdelhaleem Ali

69
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5

khaled Debuch · Answer 3 · 2018-03-20T14:16:38.240

I has solved This problem in swift 4 by adding the following lines after class ViewController:

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

I mean class Viewcontroller the class that created when you add ViewController to your project. example next class:

   class ViewController2: UIViewController ,UINavigationControllerDelegate , UIImagePickerControllerDelegate{
      // my code
    }

iOS swift NSMutableData has no member appendString

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