Swift: Trying to update NSTextField in a loop, but it only gets the last value

Question

My very simple program is looping through an array to export several files. While it\'s in the loop, I\'d like it to update a text field to tell the user which file is curre

Answer 1

Your loop is running on the main thread. The UI updates won't happen until your function finishes. Since this is taking a long time, you should do this on a background thread and then update the textfield on the main thread.

Try this:

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) {
    for item in filesArray {
        var fileName = item["fileName"]

        // Update the text field on the main queue
        dispatch_async(dispatch_get_main_queue()) {
            fileNameExportLabel.stringValue = "Exporting \(fileName).ext"
        }
        println("Exporting \(fileName).ext")

        //--code to save the stuff goes here--
    }
}

Answer 2

This workt for me on Swift 4

DispatchQueue.global(qos: .default).async {
    for item in filesArray {
        var fileName = item["fileName"]

        // Update the text field on the main queue
        DispatchQueue.main.async {
            fileNameExportLabel.stringValue = "Exporting \(fileName).ext"
        }
        print("Exporting \(fileName).ext")

        //--code to save the stuff goes here--
    }
}