iOS-optimized-custom-textfield.swift

import UIKit

public protocol SSTextFieldDelegate {
    
    public func texfieldShouldBeginEditing (textField: UITextField) -> Bool
    
    public func textFieldShouldEndEditing (textField: UITextField) -> Bool
    
    public func textFieldShouldReturn (textField: UITextField) -> Bool
    
    public func textFieldDidChanged (textField: UITextField)
}

//  Default implementation of SSTextFieldDelegate 
extension SSTextFieldDelegate{
    func texfieldShouldBeginEditing (textField: UITextField) -> Bool { return true }
    func textFieldShouldEndEditing (textField: UITextField) -> Bool { return true }
    func textFieldShouldReturn (textField: UITextField) -> Bool { return true }
    func textFieldDidChanged (textField: UITextField) { }
}


public class SSTextField: UITextField, UITextFieldDelegate {
    
    @IBInspectable var charsLimit: Int = Int.max // Initially setting limit as max
    @IBInspectable var bannedChars: String = "" // Initially no banned characters
    
    public var ssDelegate: SSTextFieldDelegate?
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        
        // Config of Textfield
        delegate = self
        autocorrectionType = .no
        spellCheckingType = .no
        clearButtonMode = .whileEditing
        
        // Adding Target to for text change
        addTarget(self, action: #selector(SSTextField.textFieldDidChange(_:)), for: .editingChanged)
        
    }
    
    func textField(_ textField: UITextField,
                   shouldChangeCharactersIn range: NSRange,
                   replacementString string: String) -> Bool {
        
        let currentString: NSString = textField.text! as NSString
        let newString: NSString = currentString.replacingCharacters(in: range, with: string) as NSString
        
        return newString.length <= charsLimit &&
            bannedChars.range(of: string, options: .caseInsensitive) == nil
    }
    
    
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        guard let delegate = ssDelegate else { return true }
        return (delegate.textFieldShouldReturn(textField: textField))
    }
    
    func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool {
        guard let delegate = ssDelegate else { return true }
        return (delegate.texfieldShouldBeginEditing(textField: textField))
    }
    
    func textFieldShouldEndEditing(_ textField: UITextField) -> Bool {
        guard let delegate = ssDelegate else { return true }
        return (delegate.textFieldShouldEndEditing(textField: textField))
    }
    
    @objc func textFieldDidChange(_ textField: UITextField){
        guard let delegate = ssDelegate else { return }
        delegate.textFieldDidChanged(textField: textField)
    }
    
}