providing a designated initializer for a custom NSView in Swift

Question

I have a custom NSView Class that looks like:

class MyClass: NSView
{
    var myClassVar: NSColor
}

Naturally, Xcode is complaining that my class has no initializers, so I need to override the designated initializer so I can initialize myClassVar.

How can I do this?

Answer 1

Try this;

       class MyClass: NSView
        {
            var myClassVar: NSColor! // the optional mark ! to be noticed.

            override init(frame frameRect: NSRect) {
                super.init(frame:frameRect);
            }

            required init(coder: NSCoder) {
                 super.init(coder: coder)
            }

            //or customized constructor/ init
            init(frame frameRect: NSRect, otherInfo:Int) {
                super.init(frame:frameRect);
                // other code
            }
        }

Answer 2

If you give your color a default value, the initializers from NSView should still work.

Here are several ways to do this:

var myClassVar: NSColor?
var myClassVar: NSColor! // make sure to set this before you actually access it
var myClassVar: NSColor = NSColor.clearColor()

The second example (implicitly unwrapped optional) is what Apple does with IBOutlets. Otherwise you would need to have an initializer that sets each of your variables to a non-null value in your init methods.

For more information about this, see Swift Initialization and the Pain of Optionals , which discusses these solutions:

• Instantiating it before the call to super.init.
• Optional variable ( NSColor? ), instantiating it after super.init
• Implicitly unwrapped optional variable ( NSColor! )
• Using a lazy property
• Using a lazy property with a closure