Swift NSCombobox DataSource Sample Code

Created By: Debasis Das (2-Feb-2016)

In this article we will implement the NSComboBoxDataSource in Swift with Autocomplete feature.

Most of the cases the NSComboBox has a static list of elements that is shown and thus the values can be stored in an array or are created in the XIB itself. however there will be scenarios when a functionality is desired where the combo box is populated at run time and thus we would need a datasource implementation.

The datasource can be implemented either in a ViewController, a window controller, a model controller or a stand alone datasource file.

In this sample code we have implemented the datasource in the app delegate.

A datasource implementation is also required to implement the auto complete functionality that is achieved through implementing the completedString method of the NSComboBox

//  AppDelegate.swift
//  NSComboBoxDataSource
//  Created by Debasis Das on 02/02/16.
//  Copyright © 2016 Knowstack. All rights reserved.

import Cocoa

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate, NSComboBoxDataSource,NSComboBoxDelegate,NSControlTextEditingDelegate {

    @IBOutlet weak var window: NSWindow!

    @IBOutlet weak var comboBox: NSComboBox!

    var dataArray = []

    var filteredDataArray:NSMutableArray = []

    func applicationDidFinishLaunching(aNotification: NSNotification)
    {
        self.comboBox.usesDataSource = true
        self.comboBox.setDelegate(self)
        self.comboBox.dataSource = self
        self.comboBox.completes = true
        
        self.dataArray = ["Debasis","John","Jane","Mary","Bill","William","Steve"]
        self.filteredDataArray = NSMutableArray(array:self.dataArray)
        


    }

    func applicationWillTerminate(aNotification: NSNotification)
    {

    }

    func numberOfItemsInComboBox(aComboBox: NSComboBox) -> Int{
        
        return self.filteredDataArray.count
    }
    
    func comboBox(aComboBox: NSComboBox, objectValueForItemAtIndex index: Int) -> AnyObject{
        return self.filteredDataArray[index] as! String
    }
    
    func comboBox(aComboBox: NSComboBox, indexOfItemWithStringValue string: String) -> Int{
        return self.filteredDataArray.indexOfObject(string)
    }

    func comboBox(aComboBox: NSComboBox, completedString string: String) -> String?{
        print("completedString")
        var returnString = ""
        for var dataString in self.dataArray{
            if  dataString.commonPrefixWithString(string, options: NSStringCompareOptions.CaseInsensitiveSearch).lengthOfBytesUsingEncoding(NSUTF8StringEncoding) == string.lengthOfBytesUsingEncoding(NSUTF8StringEncoding)
            {
                returnString = dataString as! String
                self.filterDataArray(string)
                return returnString
            }
        }
        if returnString.isEmpty{
            self.comboBox.stringValue = ""
        }
        self.filterDataArray(string)
        return returnString
    }
    
    func filterDataArray(string:String){
        print("filterDataArray \(string)")
        self.filteredDataArray = []
        if (string.isEmpty || string == "" || string == " ")
        {
            self.filteredDataArray = NSMutableArray(array: self.dataArray)
        }
        else
        {
            for var i = 0; i < dataArray.count ; i++ {
                var searchNameRange = dataArray[i].rangeOfString(string, options: NSStringCompareOptions.CaseInsensitiveSearch)
                if searchNameRange.location != NSNotFound {
                    self.filteredDataArray.addObject(dataArray[i])
                }
            }
            if self.filteredDataArray.count == 0{
                self.filteredDataArray = NSMutableArray(array: self.dataArray)
            }
        }
        print(self.filteredDataArray)
        self.comboBox.reloadData()
    }

    func comboBoxWillPopUp(notification: NSNotification) {
        if let searchStr = notification.object?.string{
            self.filterDataArray(searchStr)
        }
    }
    
    
    override func controlTextDidChange(obj: NSNotification) {
        if (obj.object?.isEqual(self.comboBox) != nil)
        {
            self.filterDataArray(self.comboBox.stringValue)
        }
        else{
            print("this should not get printed")
        }
    }

}