(Swift 3,4,5...) Fetch 1st N Headers of Search Results

Calls Search to get a message set, then downloads the 1st N messages in the message set. There are two equivalent ways of doing it: (1) iterate from 0 to N-1 and download each message individually, or (2) create a new message set that contains the 1st N messages and pass it to FetchHeaders. Both are demonstrated here.

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

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

    let imap = CkoImap()!

    // Connect to an IMAP server.
    // Use TLS
    imap.ssl = true
    imap.port = 993
    var success: Bool = imap.connect("imap.someMailServer.com")
    if success != true {
        print("\(imap.lastErrorText!)")
        return
    }

    // Login
    success = imap.login("****", password: "****")
    if success != true {
        print("\(imap.lastErrorText!)")
        return
    }

    // Select an IMAP mailbox
    success = imap.selectMailbox("Inbox")
    if success != true {
        print("\(imap.lastErrorText!)")
        return
    }

    var messageSet: CkoMessageSet?
    // We can choose to fetch UIDs or sequence numbers.
    var fetchUids: Bool = true
    // Get the message IDs of all the emails in the mailbox
    messageSet = imap.search("ALL", bUid: fetchUids)
    if imap.lastMethodSuccess == false {
        print("\(imap.lastErrorText!)")
        return
    }

    var numFound: Int = messageSet!.count.intValue
    if numFound == 0 {
        print("No messages found.")
        messageSet = nil
        return
    }

    // Get the 1st 10 messages in messageSet.
    var upperBound: Int = 10
    if numFound < upperBound {
        upperBound = numFound
    }

    var i: Int = 0
    var bUid: Bool = messageSet!.hasUids
    while i < upperBound {

        var email: CkoEmail? = imap.fetchSingleHeader(messageSet!.getId(i).intValue, bUid: bUid)
        if imap.lastMethodSuccess == false {
            print("\(imap.lastErrorText!)")
            messageSet = nil
            return

        }
        else {
            // Do whatever is needed with the email.. 
            // ....

            email = nil
        }

        i = i + 1
    }

    // Alternatively, create a new message set containing the 1st 10 message id's (UID's) 
    // from the search results message set:
    let firstTen = CkoMessageSet()!

    for i = 0; i <= upperBound - 1; i++ {
        firstTen.insertId(messageSet!.getId(i).intValue)
    }

    messageSet = nil

    // Download the 1st ten headers:
    var bundle: CkoEmailBundle?
    bundle = imap.fetchHeaders(firstTen)
    if imap.lastMethodSuccess == false {
        firstTen = nil
        print("\(imap.lastErrorText!)")
        return
    }

    // Other examples show how to iterate over the emails contained within the bundle...

    // Disconnect from the IMAP server.
    success = imap.disconnect()

    firstTen = nil
    bundle = nil

}