(Swift 3,4,5...) Adyen HMAC Signature Calculation for Hosted Payment Pages

Demonstrates how to do the HMAC Signature Calculation for a hosted payment page (HPP) in Adyen.

For a C# ASP.NET Razor Pages example showing the HTML Form with HMAC signature code, see Adyen HMAC Signature Calculation in C#

For more information, see https://docs.adyen.com/classic-integration/hosted-payment-pages/hmac-signature-calculation/

Chilkat Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

func chilkatTest() {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    var success: Bool

    var strHtml: String? = "<table class=\"od\"><tr><th>Description</th><th>Quantity</th><th>Amount</th></tr><tr><td>1 Digital Camera</td><td class=\"r\">1</td><td class=\"r\">100 GBP</td></tr><tr><td class=\"b\">Total</td><td class=\"r\"></td><td class=\"b r\">100.00 GBP</td></tr></table>"

    let gzip = CkoGzip()!
    var gzOrderData: String? = gzip.compressStringENC(strHtml, charset: "utf-8", encoding: "base64")

    let xml = CkoXml()!
    xml.tag = "keyValuePairs"

    xml.newChild2("orderData", content: gzOrderData)

    // required, The payment deadline; the payment needs to occur within the specified time value.
    var sessionValidity: String? = "2019-08-11T10:30:00Z"
    xml.newChild2("sessionValidity", content: sessionValidity)

    // optional.  Normally we'll let Adyen automatically know the country based on the IP address.
    // By default, the payment methods offered to a shopper are filtered based on the country the shopper's IP address is mapped to. 
    // In this way, shoppers are not offered payment methods that are not available in the country they are carrying out the transaction from. 
    // This IP-to-country mapping is not 100% accurate, so if you have already established the country of the shopper, you can set it explicitly 
    // in the countryCode parameter.
    var countryCode: String? = "GB"
    xml.newChild2("countryCode", content: countryCode)

    // optional
    var shopperLocale: String? = "en_GB"
    // If not specified, the locale preference is set to en_GB   by default.
    // When it is not necessary to include the country-specific part, use only the language code.
    // For example: it instead of it_IT to set the locale preferences to Italian.
    xml.newChild2("shopperLocale", content: shopperLocale)

    // required, A reference to uniquely identify the payment. This reference is used in all communication with you about the payment status. 
    // We recommend using a unique value per payment; however, it is not a requirement. If you need to provide multiple references for a transaction, 
    // you can enter them in this field. Separate each reference value with a hyphen character ("-"). This field has a length restriction: 
    // you can enter max. 80 characters.
    var merchantReference: String? = "paymentTest1234"
    xml.newChild2("merchantReference", content: merchantReference)

    // required, The merchant account identifier you want to process the (transaction) request with.
    var merchantAccount: String? = "ChilkatSoftwareIncCOM"
    xml.newChild2("merchantAccount", content: merchantAccount)

    // required.  10000 for $100.00
    var paymentAmount: String? = "10000"
    xml.newChild2("paymentAmount", content: paymentAmount)

    // required, The three-character ISO currency code
    var currencyCode: String? = "GBP"
    xml.newChild2("currencyCode", content: currencyCode)

    // required.
    var skinCode: String? = "S7uWsvfB"
    xml.newChild2("skinCode", content: skinCode)

    // optional, A unique identifier for the shopper, for example, a customer ID.
    // We recommend providing this information, as it is used in velocity fraud checks. It is also the key in recurring payments.
    // This field is mandatory in recurring payments.  
    var shopperReference: String? = "somebody@example.com"
    xml.newChild2("shopperReference", content: shopperReference)

    // optional
    var shopperEmail: String? = "somebody@example.com"
    xml.newChild2("shopperEmail", content: shopperEmail)

    // optional, An integer value that adds up to the normal fraud score.
    // The value can be either a positive or negative integer.
    xml.newChild2("offset", content: "0")

    // Apparently this is a required field.
    var shipBeforeDate: String? = "2019-06-04"
    xml.newChild2("shipBeforeDate", content: shipBeforeDate)

    xml.sort(byTag: true)

    // Encode...
    //  "\" (backslash) as "\\"
    //  ":" (colon) as "\:"

    let sbTags = CkoStringBuilder()!
    let sbValues = CkoStringBuilder()!

    let sbContent = CkoStringBuilder()!
    var n: Int = xml.numChildren.intValue
    var i: Int = 0
    while i < n {
        if i > 0 {
            sbTags.append(":")
            sbValues.append(":")
        }

        xml.getChild2(i)
        sbTags.append(xml.tag)

        sbContent.setString(xml.content)
        var numReplaced: Int = sbContent.replace("\\", replacement: "\\\\").intValue
        numReplaced = sbContent.replace(":", replacement: "\\:").intValue
        sbValues.appendSb(sbContent)
        xml.getParent2()

        i = i + 1
    }

    let sbSigningStr = CkoStringBuilder()!
    sbSigningStr.appendSb(sbTags)
    sbSigningStr.append(":")
    sbSigningStr.appendSb(sbValues)

    let crypt = CkoCrypt2()!
    crypt.hashAlgorithm = "sha256"
    crypt.macAlgorithm = "hmac"

    var hmacKey: String? = "934D1E806DDD99595EB430076FD7F8E4D12D0A3F51243A4C0C3897703118E739"
    crypt.setMacKeyEncoded(hmacKey, encoding: "hex")

    crypt.encodingMode = "base64"
    var merchantSig: String? = crypt.hmacStringENC(sbSigningStr.getAsString())

    print("\(merchantSig!)")

}