Knobility Source

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Knobility will be fully "free software" and "open source" at some point -- I want this to become "bigger than just me," with "mods" and who knows what else -- but for now I'm only ready to share parts that describe the file format, for people who want to be able to extract things from the files and/or create them.

The .knb file is literally just a hierarchy of UIView-subclassed objects -- hierarchy as in subviews of the main "desktopImageView = DesktopObject()" -- stored via NSKeyedArchiver. The following Swift 2 class files describe these objects and their NSCoding properties:

The saving is just...

       NSKeyedArchiver.archiveRootObject(self.desktopImageView, toFile: path)

and then the loading is likewise...

       view = NSKeyedUnarchiver.unarchiveObjectWithFile(path) as! UIView!

...Athough, little tip here: NSKeyedUnarchiver can seem notoriously slow (like 5 to 20 seconds!) if it's used in its (default) (semi-)asynchronous fashion. However, if you prefer not to wait around forever to actually see what you loaded, then wrap the loader and any subsequent 'immediate' usage/displaying stuff inside a dispatch_async block where you grab the main thread. Something like...

       dispatch_async(dispatch_get_main_queue(), {  // this is the magic that makes it 'fast'
                view = NSKeyedUnarchiver.unarchiveObjectWithFile(path) as! UIView!

                self.addMultipleObjectsToGear(view) // or whatever
                view.setNeedsDisplay()   //etc
       })

Ok, have fun! Let me know what you come up with!

-Scott Hawley, 9/13/2015

P.S.- One last thing: Seems that NSCoding can be a little stingy about encoding images stored "Assets" subdirectories of Xcode projects. So, the .knb file generally may NOT contain the image of the knob, that's why KnobObject.swift is always creating a knob from scratch. Here's the image in question: link to image of default knob.