Resize NSImage Proportionally (Swift)

I wanted a simple function to resize an image to a desired height, while keeping proportions. Here’s what I came up with (based on Marco implementation):

extension NSImage {


    func resizedImageTo(sourceImage: NSImage, newSize: NSSize) -> NSImage?{

        if sourceImage.isValid == false {

            return nil


        let representation = NSBitmapImageRep(bitmapDataPlanes: nil, pixelsWide: Int(newSize.width), pixelsHigh: Int(newSize.height), bitsPerSample: 8, samplesPerPixel: 4, hasAlpha: true, isPlanar: false, colorSpaceName: .calibratedRGB, bytesPerRow: 0, bitsPerPixel: 0)

        representation?.size = newSize



        NSGraphicsContext.current = NSGraphicsContext.init(bitmapImageRep: representation!)

        sourceImage.draw(in: NSRect(x: 0, y: 0, width: newSize.width, height: newSize.height), from: NSZeroRect, operation: .copy, fraction: 1.0)



        let newImage = NSImage(size: newSize)



        return newImage






Questions / comments / suggestions? I’m at @MarcMasVi 


Updated after I discovered the great implementation Marco Arment suggested. 

Get Date Day, Month or Year in Swift 3.0

Just a quick update to show how to get Date Day, Month or Year in Swift 3

//Here I’m creating the calendar instance that we will operate with:

let calendar = NSCalendar.init(calendarIdentifier: NSCalendar.Identifier.gregorian)



//Now asking the calendar what month are we in today’s date:

let currentMonthInt = (calendar?.component(NSCalendar.Unit.month, from: Date()))!



//Now asking the calendar what year are we in today’s date:

let currentYearInt = (calendar?.component(NSCalendar.Unit.year, from: Date()))!


Hope this proves useful.

If you would have any suggestions on how to improve reach me @MarcMasVi in Twitter. 


Undo functionality in Core Data (Swift 3)

If you’re developing a Core Data based application for Mac, wouldn’t it be great if you could add undo support?

Well, turns out that is a couple of lines away. Follow the simple steps:

1. Make sure your managedObjectContext has an undo manager, without it Core Data can’t keep track of the changes:

         managedObjectContext?.undoManager = UndoManager() 

2. In the viewController where you should handle the undo operation just add:

      func undo(_ sender: AnyObject?){




        refreshTable() //If applicable (for instance if you don’t use bindings)

        re-fetch the information and reload the table. This is what this

        function does in my code



And that’s it, now you have full undo functionality! You’ll see how in the menus Undo no longer appears greyed out.

Questions / comments? I’m at @MarcMasVi 


Sorting Multi Dimensional Array (Swift 3)

Hello all, 

This one I’ve found specially useful when working with Core Data fetched arrays. 

Let’s say that we want to sort the result of a fetch request based on the value of the field “gold”, we would therefore do the following:

let dwarfGoldBags = … //Contains the result of a fetch request with one of the fields named “gold” and being an integer.


We will now proceed to sort the array and store it in sortedGoldArray:

let sortedGoldArray = dwarfGoldBags.sorted { ($0.goldas Int) > ($1.goldas Int) } 


If instead of core data you have a multi-dimensional array it would be as easy as:

let sortArray = originalArray.sorted { ($0.[0] as Int) > ($1.[0] as Int) } 


In this case we’re comparing the values stored in the first value of the subArrays. 

Questions / comments? I’m at @MarcMasVi 


Dates & Components in Swift 3.0

The way we work with dates has changed in Swift 3, the change makes it’s way simpler then before. Let’s look at an example:

//CreateDateFromComponents (1st January 2017)

            var newDate = Date()

            let newDateComponents = DateComponents(calendar: Calendar.current, timeZone: nil, era: nil, year: 2017, month: 1, day: 1, hour: nil, minute: nil, second: nil, nanosecond: nil, weekday: nil, weekdayOrdinal: nil, quarter: nil, weekOfMonth: nil, weekOfYear: nil, yearForWeekOfYear: nil)

            newDate = newDateComponents)!


Hope this proves useful. If you would have any suggestions on how to improve you know where to reach me, @MarcMasVi in Twitter.




Scheduled notifications in macOS

Notifications are a very useful addition to macOS applications, when done right can help inmensly. 

Here’s how you create scheduled and immediate notifications. Let’s start with the immediate ones:

func triggerNotification() -> Void {

    let notification = NSUserNotification()

    notification.title = “titleOfNotification”

    notification.informativeText = “whateverTextYou WantToAdd”

    notification.soundName = NSUserNotificationDefaultSoundName



This will trigger a notification the moment you execute it, if however you would like to schedule a notification for a later date you can do:

func showNotification(atDate: NSDate) -> Void {

    let notification = NSUserNotification()

    notification.title = “It’s MONTH”

    notification.informativeText = “Time to check your finances!”

    notification.soundName = NSUserNotificationDefaultSoundName

    notification.deliveryDate = NSDate().dateByAddingTimeInterval(5.0)

    //notification.deliveryDate = getDateOfNextNotification()



In this case you would be showing the notification after 5 seconds, more useful though is to plan it for a later date, like you can see in my commented code. The getDateOfNextNotification function simply returns the NSDate where I would like the notification to trigger. 

If you plan to use this, for instance in App Delegate, you may want to check if you have already scheduled notification to avoid duplicates. You can do the following:

func scheduleUpcomingAlertNotification() -> Void {

    let pipeOfNotifications = NSUserNotificationCenter.defaultUserNotificationCenter().scheduledNotifications.count

    if( pipeOfNotifications > 0){


    }else trigger the function

Questions / comments? I’m at @MarcMasVi 


Copy one or multiple NSTableView rows, Swift

So here’s a simple yet tricky one: you’ve created your NSTableView but now you would like to allow a user to copy to the clipboard one, or a couple of rows. How do you do it?

1. Implement the function copy (func copy(sender: AnyObject?){}), do not confuse with the method for duplicating an object

 2. Get the index set from the tableView selection and retrieve the relevant rows from your dataSource. From there is just a matter of composing the text to copy into the pasteboard. 

Here’s my code structure, implemented in my NSTableViewController:

func copy(sender: AnyObject?){


        var textToDisplayInPasteboard = “”

        let indexSet = tableView.selectedRowIndexes

        for (_, rowIndex) in indexSet.enumerate() {

            var iterator: CoreDataOjectType


            textToDisplayInPasteboard = (! 


        let pasteBoard = NSPasteboard.generalPasteboard()


        pasteBoard.setString(textToDisplayInPasteboard, forType:NSPasteboardTypeString)



This will also automatically enable the Edit -> Copy (Command + C) menu, that would be disabled -grayed out- without this code. 

Questions / comments? I’m at @MarcMasVi 


Easy Core Data CSV Exporter in Swift

A new app I’m working on has a Core Data back end and I wanted to implement a quick way to export all the entities into a CSV file and dump it into the Desktop. 

Here are the snippets to do it:

1. Make sure you get the NSObjects you want to export (in this case I use a function that will return an array with the fetched NSObjectSubclass Transaction)

   private func provideAllTransactions() -> Array<Transaction>{

        let fetchRequest = NSFetchRequest(entityName: “Transaction”)

        fetchRequest.sortDescriptors = [NSSortDescriptor(key: “date”, ascending: false), NSSortDescriptor(key: “concept”, ascending: true)]

        return try! managedObjectContext.executeFetchRequest(fetchRequest) as! Array<Transaction>


2. Convert to text, properly separating by commas and lines

    private func convertTransactionsToCsvString(transactions: Array<Transaction>)->String{

        var result = “HEADER 1, HEADER 2, HEADER 3, \r”//Headers


        for transactionIterator in transactions{ //Data

            result = result + “\”” + (transactionIterator.accountItBelongsTo?.name)! + “\”” + “,”

            result = result + “\”” + ((! ?? NSDate().description

            result = result + “\”” + “,” + “\”” + (transactionIterator.concept)! + “\””

            result = result + “\”” + “\r”



        return result


3. Save to a path 

    func exportAllToCsv() -> Bool{


        let contentsToWrite = convertTransactionsToCsvString(provideAllTransactions())


        //Select path

        let path = “/Users/USER_NAME/Desktop/csvTest.csv”

        //Try to save it

        do {

            try contentsToWrite.writeToFile(path, atomically: true, encoding: NSUTF8StringEncoding)


            print(“ERROR: Export could not be saved in %”, path)



        return true



Note that in this example the path is hardcoded to the desktop of the user named USER_NAME, you should have the user choose where he wants to save it or you can hardcode a location in your disk. 

If you would have a NSDictionary it would be almost the same but starting at point 2 with the dictionary results. 

Questions / comments? I’m at @MarcMasVi



PS. Here is how you would have the path be selected by the user:        


    privatefunc userToChooseAFileInModalPannel() -> String?{

        let pannel: NSOpenPanel = NSOpenPanel()

        pannel.canChooseDirectories = true

        pannel.canChooseFiles = false

        pannel.allowsMultipleSelection = false



        return pannel.URL?.path


 then in point 3 you would do 

//Select path

        let path = userToChooseAFileInModalPannel() + “/test.csv”

Switching NSViewControllers from NSWindowController

This has taken quite some time to crack as there was not that much available information online. 

I wanted a very simple way to change the NSViewController of a window on the fly by using code. 

Screen Shot 2015 12 07 at 18 41 33

The solution I ended up with is quite easy, on the NSWindowController I load the default NSViewController by typing in windowDidLoad():

let viewController = storyboard?.instantiateControllerWithIdentifier(“nsviewcontroller1″) as! NSViewController

        self.window?.contentViewController = viewController

Afterwards, when I want to change NSViewController1 by NSViewController2 i just have a button in my toolbar linked to the following action:

@IBAction func showController2(sender: NSToolbarItem){

        let viewController = storyboard?.instantiateControllerWithIdentifier(nsviewcontroller2) as! NSViewController

        self.window?.contentViewController = viewController


That’s about it, extremely simple, but took me quite a bit to develop. 

As always if you have any feedback I’m at @MarcMasVi