Simple Animation TextField Swift 4

This is how to create animation with cocoapod library, ok I will give an example with library AnimatedTextInput . 

Use cocoapods to install this custom control in your project.

pod 'AnimatedTextInput'

how to use it is quite easy,  see the coding below

import UIKit
import AnimatedTextInput

class TextInputViewController: UIViewController {
    @IBOutlet weak var labelT: UILabel!
    @IBOutlet weak var textAnimate: AnimatedTextInput!
    
    
    override func viewDidLoad() {
        super.viewDidLoad()
        textAnimate.placeHolderText = "Paswword"
        textAnimate.style = CustomTextInputStyle()
        textAnimate.type = .password(toggleable: true)
    }

}

struct CustomTextInputStyle: AnimatedTextInputStyle {
    let placeholderInactiveColor = UIColor.gray
    let activeColor = #colorLiteral(red: 0.4588235294, green: 0.7176470588, blue: 0.1803921569, alpha: 1)
    let inactiveColor = UIColor.gray.withAlphaComponent(0.3)
    let lineInactiveColor = UIColor.gray.withAlphaComponent(0.3)
    let lineActiveColor = UIColor.gray.withAlphaComponent(0.3)
    let lineHeight: CGFloat = 1
    let errorColor = UIColor.red
    let textInputFont = UIFont.systemFont(ofSize: 14)
    let textInputFontColor = UIColor.black
    let placeholderMinFontSize: CGFloat = 12
    let counterLabelFont: UIFont? = UIFont.systemFont(ofSize: 12)
    let leftMargin: CGFloat = 0
    let topMargin: CGFloat = 20
    let rightMargin: CGFloat = 0
    let bottomMargin: CGFloat = 10
    let yHintPositionOffset: CGFloat = 7
    let yPlaceholderPositionOffset: CGFloat = 0
    public let textAttributes: [String: Any]? = nil
}