import UIKit

class SCUnderlineTextField: SCTextField {
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.font = SCFonts.largeSizeFont(SCFonts.fontType.medium)
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        let bottomBorder = CALayer()
        bottomBorder.frame = CGRect(
            x: 0.0,
            y: self.frame.size.height - 2.0,
            width: self.frame.size.width,
            height: 2.0
        )
        bottomBorder.backgroundColor = UIColor.spycodesGrayColor().cgColor

        self.layer.addSublayer(bottomBorder)
    }
}

import UIKit

class SCUnderlineTextField: SCTextField {
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.font = SCFonts.largeSizeFont(SCFonts.fontType.regular)
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        let bottomBorder = CALayer()
        bottomBorder.frame = CGRect(
            x: 0.0,
            y: self.frame.size.height - 1.0,
            width: self.frame.size.width,
            height: 1.0
        )
        bottomBorder.backgroundColor = UIColor.spycodesGrayColor().cgColor

        self.layer.addSublayer(bottomBorder)
    }
}

--- 
+++ 
@@ -3,7 +3,7 @@
 class SCUnderlineTextField: SCTextField {
     required init?(coder aDecoder: NSCoder) {
         super.init(coder: aDecoder)
-        self.font = SCFonts.largeSizeFont(SCFonts.fontType.regular)
+        self.font = SCFonts.largeSizeFont(SCFonts.fontType.medium)
     }
 
     override func layoutSubviews() {
@@ -12,9 +12,9 @@
         let bottomBorder = CALayer()
         bottomBorder.frame = CGRect(
             x: 0.0,
-            y: self.frame.size.height - 1.0,
+            y: self.frame.size.height - 2.0,
             width: self.frame.size.width,
-            height: 1.0
+            height: 2.0
         )
         bottomBorder.backgroundColor = UIColor.spycodesGrayColor().cgColor
 
Use thicker font and height for underlined text fields
