UITextField+Extensions.swift

import UIKit

extension UITextField
{
    class func connectFields(fields:[UITextField]) -> Void
    {
        guard let last = fields.last else {
            return
        }
        for i in 0 ..< fields.count - 1
        {
            fields[i].returnKeyType = .next
            fields[i].addTarget(fields[i + 1], action: #selector(UIResponder.becomeFirstResponder), for: .editingDidEndOnExit)
        }
        last.returnKeyType = .go
        last.addTarget(last, action: #selector(UIResponder.resignFirstResponder), for: .editingDidEndOnExit)
    }
    
    func underlined(color: UIColor)
    {
        let border = CALayer()
        let width = CGFloat(2)
        border.borderColor = color.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
    }
}