How to Convert String to Unicode(Utf-8) String in Swift

How to convert string to unicode(UTF-8) string in Swift?

Swift 4 and 5 I have created a String extension

extension String {
    func utf8DecodedString()-> String {
        let data = self.data(using: .utf8)
        let message = String(data: data!, encoding: .nonLossyASCII) ?? ""
        return message
    }
    
    func utf8EncodedString()-> String {
        let messageData = self.data(using: .nonLossyASCII)
        let text = String(data: messageData!, encoding: .utf8) ?? ""
        return text
    }
}

How convert string to utf-8? (Swift, Alamofire)

Swift 3

let newStr = String(utf8String: stringToDecode.cString(using: .utf8)!)

Source StackOverFlow

Can the conversion of a String to Data with UTF-8 encoding ever fail?

UTF-8 can represent all valid Unicode code points, therefore a conversion
of a Swift string to UTF-8 data cannot fail.

The forced unwrap in

let string = "some string .."
let data = string.data(using: .utf8)!

is safe.

The same would be true for .utf16 or .utf32, but not for
encodings which represent only a restricted character set,
such as .ascii or .isoLatin1.

You can alternatively use the .utf8 view of a string to create UTF-8 data,
avoiding the forced unwrap:

let string = "some string .."
let data = Data(string.utf8)

Decode string using UTF-8 in swift 5

This is the output you get if at some point UTF-8 data was interpreted as Latin1. For example:

let s = "Kawran Bazar FDC Road, East Nakhalpara, নিকেতন, ঢাকা, ঢাকা বিভাগ, বাংলাদেশ"
let utf8Data = Data(s.utf8)
let latin1 = String(data: utf8Data, encoding: .isoLatin1)!
print(latin1)

==> 

Kawran Bazar FDC Road, East Nakhalpara, নিà¦à§à¦¤à¦¨, ঢাà¦à¦¾, ঢাà¦à¦¾ বিভাà¦, বাà¦à¦²à¦¾à¦¦à§à¦¶

You should first try to fix this and remove this incorrect string creation. If you cannot, then you can round-trip it back through Latin1.

let latin1Data = latin1.data(using: .isoLatin1)!
let utf8String = String(data: latin1Data, encoding: .utf8)!

utf8String == s // true

Convert String to Data base HTTP.UTF8 in swift

Your question is difficult to understand as you don't explain what "ExpDate":"ZIT5KR2+4Mk=" is. In which part is it contained? I assume ExpDate is a property param dictionary that's serialized into JSON. I further assume that the plus character is the original character after the Base64 encoding and wasn't inserted when the URL request was built.

Your server obviously expects a POST request with URL encoded form data. This kind of request is natively supported by Android (UrlEncodedFormEntity) but not by iOS. To achieve the same, you cannot just concatenate the key/value pairs. You must properly URL encode them as well.

To that end, I propose the following URLRequest extension:

import Foundation

extension URLRequest {

    private static let alloweCharacters = CharacterSet(charactersIn: "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 -_.*")

    public mutating func setURLEncodedFormData(parameters: [String: String?]) {

        var encodedParameters = ""

        for (key, value) in parameters {

            if !encodedParameters.isEmpty {
                encodedParameters += "&"
            }

            encodedParameters += URLRequest.urlEncoded(value: key)
            encodedParameters += "="
            if let value = value {
                encodedParameters += URLRequest.urlEncoded(value: value)
            }
        }

        self.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
        self.httpBody = encodedParameters.data(using: .utf8)
    }

    private static func urlEncoded(value: String) -> String {

        return value.addingPercentEncoding(withAllowedCharacters: alloweCharacters)!.replacingOccurrences(of: " ", with: "+")
    }

}

It can be used like this (tested in Playground):

var request = URLRequest(url: URL(string: "http://somehost.com/someservice")!)
request.httpMethod = "POST"

let jsonString = "{ \"ExpDate\" : \"ZIT5KR2+4Mk=\", \"SomeString\" : \"%=&\" }"
var params = [ "action": "payment", "key": "hmn@$Q&*$GD4@!$#", "input": jsonString]
request.setURLEncodedFormData(parameters: params)

I hope it solves your problem.

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