Swift
Force Quoted-Printable Encoding for Email

Demonstrates how to force the quoted-printable encoding for email.
Chilkat Swift Downloads

Swift

func chilkatTest() {
    var success: Bool = false

    let email = CkoEmail()!

    email.subject = "test"
    email.from = "bob@example.com"
    email.add(to: "Mary", emailAddress: "mary@example.com")

    // Add plain-text and HTML alternative bodies.
    // Include some "=" chars so we can see the quoted-printable encoding when used..
    email.addPlainTextAlternativeBody(body: "This is a test == Hello World!")
    email.addHtmlAlternativeBody(body: "<html><body>This is a test == Hello World!</body></html>")

    // Examine the MIME of the email to see that it does not use quoted-printable.
    // (If the email contained non-usascii chars, it would automatically use quoted-printable.)
    let mailman = CkoMailMan()!
    print("\(mailman.render(toMime: email)!)")

    // Here is the MIME before forcing quoted-printable.
    // Notice the Content-Transfer-Encoding is "7bit" (not "quoted-printable")

    // MIME-Version: 1.0
    // Date: Tue, 29 Sep 2020 12:26:52 -0500
    // Message-ID: <CF274FC0A2F82B98A05B7507DF7DFB966A2C0EB8@CHILKATSLICE>
    // Content-Type: multipart/alternative;
    //  boundary="------------080901080902080000030208"
    // X-Priority: 3 (Normal)
    // Subject: test
    // From: bob@example.com
    // To: Mary <mary@example.com>
    // 
    // --------------080901080902080000030208
    // Content-Transfer-Encoding: 7bit
    // Content-Type: text/plain; charset=us-ascii; format=flowed
    // 
    // This is a test == Hello World!
    // --------------080901080902080000030208
    // Content-Transfer-Encoding: 7bit
    // Content-Type: text/html; charset=us-ascii
    // 
    // <html><body>This is a test == Hello World!</body></html>
    // --------------080901080902080000030208--

    print("----")

    // To force quoted-printable, set the Content-Transfer-Encoding header.
    // It will automatically propagate as needed to the MIME sub-parts.
    email.addHeaderField(fieldName: "Content-Transfer-Encoding", fieldValue: "quoted-printable")
    print("\(mailman.render(toMime: email)!)")

    // MIME-Version: 1.0
    // Date: Tue, 29 Sep 2020 12:26:52 -0500
    // Message-ID: <F36B276E3A720FE5111D15CE9142C8909E1F5AB9@CHILKATSLICE>
    // Content-Type: multipart/alternative;
    //  boundary="------------080901080902080000030208"
    // X-Priority: 3 (Normal)
    // Subject: test
    // From: bob@example.com
    // To: Mary <mary@example.com>
    // 
    // --------------080901080902080000030208
    // Content-Transfer-Encoding: quoted-printable
    // Content-Type: text/plain; charset=us-ascii; format=flowed
    // 
    // This is a test =3D=3D Hello World!
    // --------------080901080902080000030208
    // Content-Transfer-Encoding: quoted-printable
    // Content-Type: text/html; charset=us-ascii
    // 
    // <html><body>This is a test =3D=3D Hello World!</body></html>
    // --------------080901080902080000030208--

}