Initialize Swift subclass of UIView, designed in .xib

gistfile1.swift

// Create CustomView.xib, set File's Owner to CustomView. 

class CustomView : UIView {
    
    // other outlets
    
    override init(frame: CGRect) { // for using CustomView in code
        super.init(frame: frame)
        self.commonInit()
    }
    
    required init?(coder aDecoder: NSCoder) { // for using CustomView in IB
        super.init(coder: aDecoder)
        self.commonInit()
    }
    
    private func commonInit() {
        // for IBDesingable usage
        #if !TARGET_INTERFACE_BUILDER
            let bundle = NSBundle.mainBundle()
        #else
            let bundle = NSBundle.init(forClass: self.dynamicType)
        #endif
        // parsing xib name from class
        let className = NSStringFromClass(self.dynamicType)
        let names = className.componentsSeparatedByString(".")
        if let viewString = names.last,
            let view = bundle.loadNibNamed(viewString, owner: self, options: nil).first as? UIView
            where names.count == 2 {
                view.frame = self.layer.bounds;
                view.autoresizingMask = [.FlexibleWidth, .FlexibleHeight]
                self.addSubview(view)
        }
    }
}