Swift Custom UIView Inherited by UILabel - swift

Question

I have an inheritance problem that I'm trying to solve. Typically, I'd just use multi-inheritance here, but Swift doesn't really do that.
Custom UIView
import UIKit
class ValidationView: UIView {
var required:Bool = false
var validRegex:String? = nil
var requiredLbl:UILabel?
private var requiredColor:UIColor = UIColor.red
private var requiredText:String = "*"
private var requiredFont:UIFont = UIFont.systemFont(ofSize: 16.0, weight: UIFont.Weight.bold)
override init(frame: CGRect) {
super.init(frame: frame)
self.setupValidationViews()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
self.setupValidationViews()
}
private func setupValidationViews() {
self.requiredLbl = UILabel(frame: CGRect(x: self.frame.width - 30, y: 30, width: 20, height: 20))
self.styleRequiredLabel()
self.addSubview(self.requiredLbl!)
}
func styleRequiredLabel(color:UIColor?, text:String?, font:UIFont?) {
self.requiredColor = color ?? self.requiredColor
self.requiredText = text ?? self.requiredText
self.requiredFont = font ?? self.requiredFont
self.styleRequiredLabel()
}
private func styleRequiredLabel() {
self.requiredLbl?.textColor = self.requiredColor
self.requiredLbl?.text = self.requiredText
self.requiredLbl?.font = self.requiredFont
}
}
Custom UITextField
import Foundation
import UIKit
#IBDesignable open class CustomTextField: UITextField {
#IBInspectable public var borderWidth: CGFloat = 2.0 {
didSet {
layer.borderWidth = borderWidth
}
}
#IBInspectable public var borderColor: UIColor = UIColor.lightGray {
didSet {
layer.borderColor = borderColor.cgColor
}
}
#IBInspectable public var cornerRadius: CGFloat = 4.0 {
didSet {
layer.cornerRadius = cornerRadius
layer.masksToBounds = true
}
}
}
I want that Custom UITextField to also be a ValidationView. I know I could do a protocol and extension and then have my CustomTextField implement that protocol, but that doesn't allow for init overrides. I'd rather not have to change the inits on ever view that implements ValidationView.
Something like this can be accomplished using #arturdev answer. I ended up with this:
import UIKit
class ValidatableProperties {
var required:Bool
var validRegex:String?
var requiredColor:UIColor
var requiredText:String
var requiredFont:UIFont
init(required:Bool, validRegex:String?, requiredColor:UIColor, requiredText:String, requiredFont:UIFont) {
self.required = required
self.validRegex = validRegex
self.requiredText = requiredText
self.requiredColor = requiredColor
self.requiredFont = requiredFont
}
}
protocol Validatable : UIView {
var validatableProperties:ValidatableProperties! { get set }
var requiredLbl:UILabel! { get set }
func setupValidationDefaults()
func setupValidationViews(frame:CGRect)
func styleRequiredLabel(color:UIColor?, text:String?, font:UIFont?)
}
extension Validatable {
func setupValidationDefaults() {
let props = ValidatableProperties(required: false, validRegex: nil, requiredColor: UIColor.red, requiredText: "*", requiredFont: UIFont.systemFont(ofSize: 16.0, weight: .bold))
self.validatableProperties = props
}
func setupValidationViews(frame:CGRect) {
self.requiredLbl = UILabel(frame: CGRect(x: frame.width, y: 0, width: 20, height: 20))
self.styleRequiredLabel()
self.addSubview(self.requiredLbl)
}
func styleRequiredLabel(color:UIColor?, text:String?, font:UIFont?) {
self.validatableProperties.requiredColor = color ?? self.validatableProperties.requiredColor
self.validatableProperties.requiredText = text ?? self.validatableProperties.requiredText
self.validatableProperties.requiredFont = font ?? self.validatableProperties.requiredFont
self.styleRequiredLabel()
}
private func styleRequiredLabel() {
self.requiredLbl.textColor = self.validatableProperties.requiredColor
self.requiredLbl.text = self.validatableProperties.requiredText
self.requiredLbl.font = self.validatableProperties.requiredFont
}
}
open class ValidationTextField:UITextField, Validatable {
var requiredLbl: UILabel!
var validatableProperties: ValidatableProperties!
override public init(frame: CGRect) {
super.init(frame: frame)
self.setupValidationDefaults()
self.setupValidationViews(frame: frame)
}
public required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
self.setupValidationDefaults()
self.setupValidationViews(frame: self.frame)
}
}
But this requires extending all classes you want validatable into their own custom classes, needing to overwrite the inits every time and call the methods. It works, but it's not ideal and, while not exactly anti-pattern inheritance, certainly has some code-smell to it.

Answer 1

You should make ValidationView as protocol instead of class, and conform your custom classes to that protocol.
ValidatableView.swift
import UIKit
fileprivate var requiredColor = UIColor.red
fileprivate var requiredText = "*"
fileprivate var requiredFont = UIFont.systemFont(ofSize: 16.0, weight: UIFont.Weight.bold)
fileprivate struct AssociatedKeys {
static var lblKey = "_lblKey_"
}
protocol ValidatableView: class {
var required: Bool {get}
var validRegex: String? {get}
var requiredLbl: UILabel? {get}
}
extension ValidatableView where Self: UIView {
var required: Bool {
return false
}
var validRegex: String? {
return nil
}
var requiredLbl: UILabel? {
get {
return objc_getAssociatedObject(self, &AssociatedKeys.lblKey) as? UILabel
}
set {
objc_setAssociatedObject(self, &AssociatedKeys.lblKey, newValue, .OBJC_ASSOCIATION_RETAIN)
}
}
func setupValidation() {
self.requiredLbl = UILabel(frame: CGRect(x: self.frame.width - 30, y: 30, width: 20, height: 20))
self.requiredLbl?.autoresizingMask = .flexibleWidth
self.styleRequiredLabel()
self.addSubview(self.requiredLbl!)
}
func styleRequiredLabel(color:UIColor? = requiredColor, text:String? = requiredText, font:UIFont? = requiredFont) {
self.requiredLbl?.textColor = requiredColor
self.requiredLbl?.text = requiredText
self.requiredLbl?.font = requiredFont
}
}
CustomTextField.swift
#IBDesignable open class CustomTextField: UITextField {
#IBInspectable public var borderWidth: CGFloat = 2.0 {
didSet {
layer.borderWidth = borderWidth
}
}
#IBInspectable public var borderColor: UIColor = UIColor.lightGray {
didSet {
layer.borderColor = borderColor.cgColor
}
}
#IBInspectable public var cornerRadius: CGFloat = 4.0 {
didSet {
layer.cornerRadius = cornerRadius
layer.masksToBounds = true
}
}
public override init(frame: CGRect) {
super.init(frame: frame)
setupValidation()
}
public required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
setupValidation()
}
}
extension CustomTextField: ValidatableView { //<- Magic line :)
}

Answer 2

You can create an instance of ValidationView when you instantiate CustomTextField.
Something like this:
#IBDesignable open class CustomTextField: UITextField {
var validationView: ValidationView
override init(frame: CGRect) {
super.init(frame: .zero)
self.validationView = ValidationView()
}
}