Adds border, corner radius, and padding to the UITextField. These properties can be set via the attribute inspector in storyboard.

CustomTextField.swift

import UIKit

@IBDesignable
class CustomTextField: UITextField {
    
    var padding: UIEdgeInsets {
        get {
            return UIEdgeInsets(top: 0, left: paddingValue, bottom: 0, right: paddingValue)
        }
    }
    
    override func textRectForBounds(bounds: CGRect) -> CGRect {
        return UIEdgeInsetsInsetRect(bounds, padding)
    }
    
    override func placeholderRectForBounds(bounds: CGRect) -> CGRect {
        return UIEdgeInsetsInsetRect(bounds, padding)
    }
    
    override func editingRectForBounds(bounds: CGRect) -> CGRect {
        return UIEdgeInsetsInsetRect(bounds, padding)
    }
    
    @IBInspectable var paddingValue: CGFloat = 0
    
    
    @IBInspectable var borderColor: UIColor? = UIColor.clearColor() {
        didSet {
            layer.borderColor = self.borderColor?.CGColor
        }
    }
    @IBInspectable var borderWidth: CGFloat = 0 {
        didSet {
            layer.borderWidth = self.borderWidth
        }
    }
    @IBInspectable var cornerRadius: CGFloat = 0 {
        didSet {
            layer.cornerRadius = self.cornerRadius
            layer.masksToBounds = self.cornerRadius > 0
        }
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
    
    override init(frame: CGRect) {
        super.init(frame: frame)
    }
    
    override func drawRect(rect: CGRect) {
        self.layer.cornerRadius = self.cornerRadius
        self.layer.borderWidth = self.borderWidth
        self.layer.borderColor = self.borderColor?.CGColor
    }
}