CustomTableHeaderView.swift

class CustomTableHeaderView: UIView {
    
    //MARK: Property
    let label = UILabel(frame: CGRectZero)
    let backbutton = UIButton(frame: CGRectZero)
    
    
    //MARK: Method
    override init(frame: CGRect) {
        super.init(frame: frame)
        label.text =  "Add custom location"
        label.textAlignment = .Center
        backbutton.setImage(UIImage(named: "icon-backArrow-black"), forState: UIControlState.Normal)
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    //TODO: Remove adding of subviews etc
    override func layoutSubviews() {
        
        super.layoutSubviews()
        label.frame = self.frame
        backbutton.frame = CGRect(x: 16, y: 0, width: 20, height: self.frame.height)
        
        self.addSubview(label)
        self.addSubview(backbutton)
        
        
        let border = CALayer()
        let width = CGFloat(0.8)
        
        //default gray color on UITableViewSeparator
        border.borderColor = UIColor(red: 0.783922, green: 0.780392, blue: 0.8, alpha: 1.0).CGColor
        border.frame = CGRect(x: 0, y: self.frame.size.height - width, width:  self.frame.size.width, height: self.frame.size.height)
        
        border.borderWidth = width
        self.layer.addSublayer(border)
        self.layer.masksToBounds = true
    }
}

for the

required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
}

remove the fatalError and pop in super.init(coder: aDecoder) and then you can add your setup() function in there after the super.init(coder: aDecoder) gets called

don't forget that layoutSubviews() can get called multiple times on a view, so we don't want to add subviews or do any sort of configuration other than reframing/repositioning in there... any border properties like color and size should be moved to the setup() function as well