Errata

The paragraph says: "If an instance of this UIView subclass appears in the nib, then its self-configuration methods, such as init(coder:) and willMoveToSuperView:, will be compiled and run and the nib editor prepares to prepare your view. For example, if your view's init(coder:) method adds a UILabel as a subview of this view, then the nib editor will show that label."

Perhaps surprisingly, this is not the case. The initializer that will run is init(frame:), not init(coder:). This is easily confirmed with a snippet such as:

@IBDesignable
class DesignableView: UIView {
let myColor: UIColor
override init(frame: CGRect) {
self.myColor = UIColor.redColor()
super.init(frame: frame)
}

required init?(coder aDecoder: NSCoder) {
self.myColor = UIColor.greenColor()
super.init(coder: aDecoder)
}

override func drawRect(rect: CGRect) {
super.drawRect(rect)
self.myColor.setFill()
UIBezierPath(rect: self.bounds).fill()
}
}

You will see a red rectangle, not a green one. If you remove the init(frame:) initializer in this snippet, the IBDesignable agent will crash.

Note from the Author or Editor:
This must be right, because the submitter has clearly tested it out, but I haven't tested yet. I'll take it under advisement, making a note in my copy of the manuscript. And of course this erratum will be here to help others; the submitter has explained the matter with utmost clarity.