Add button programmatically - ios

Question

I want to make a button appear when there are 1 or more characters in a text field.
Currently, I have 3 problems:
I can't use the #objc if I do that then I get the following error "#objc can only be used with members of classes, #objc protocols, and concrete extensions of classes".
So basically I can't use the button.
I want to add constraints to the button, but on some of those I want the Safe Area to be the "toItem" but I don't know which "name" it has for that, I used view.safeAreaInsets but I'm not sure if that's the right way to do it.
I want to check how many characters there are in a text field (so I want the button to appear the moment that the user types a letter).
I would think it has to be done in an if statement but I don't know how to check for the characters in a text field.
This is my code for the first problem:
addButton.addTarget(self, action: #selector(buttonAction(_ :)), for: .touchUpInside)
self.view.addSubview(addButton)
#objc func buttonAction(_ : UIButton) {
}
This is for the second one:
let buttonRightConstraint = NSLayoutConstraint(item: addButton, attribute: .right, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view.safeAreaInsets, attribute: .right, multiplier: 1.0, constant: 16)
let buttonTopConstraint = NSLayoutConstraint(item: addButton, attribute: .top, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view.safeAreaInsets , attribute: .top , multiplier: 1.0, constant: 16)
This is for the third one:
if (TextFieldName.text!.count > 0) {
}
This is my total code:
import UIKit
extension AddWorkoutController {
func hideKeyboard() {
let tap:UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(dismissKeyboard))
view.addGestureRecognizer(tap)
}
#objc func dismissKeyboard() {
view.endEditing(true)
}
}
class AddWorkoutController: UIViewController {
#IBOutlet weak var TextFieldName: UITextField!
let addButton = UIButton(type: UIButton.ButtonType.custom) as UIButton
override func viewDidLoad() {
super.viewDidLoad()
configureTextFields()
self.hideKeyboard()
addButton.setBackgroundImage(UIImage(named: "Add-Button"), for: UIControl.State.normal)
addButton.setTitle("", for: UIControl.State.normal)
let buttonRightConstraint = NSLayoutConstraint(item: addButton, attribute: .right, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view.safeAreaInsets, attribute: .right, multiplier: 1.0, constant: 16)
let buttonTopConstraint = NSLayoutConstraint(item: addButton, attribute: .top, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view.safeAreaInsets , attribute: .top , multiplier: 1.0, constant: 16)
let buttonHeightConstraint = NSLayoutConstraint(item: addButton, attribute: .height, relatedBy: NSLayoutConstraint.Relation.equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 32)
let buttonWidthConstraint = NSLayoutConstraint(item: addButton, attribute: .width, relatedBy: NSLayoutConstraint.Relation.equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 64)
addButton.addTarget(self, action: #selector(buttonAction(_ :)), for: .touchUpInside)
self.view.addSubview(addButton)
self.view.addConstraints([buttonRightConstraint, buttonTopConstraint, buttonHeightConstraint, buttonWidthConstraint])
#objc func buttonAction(_ : UIButton) {
}
if (TextFieldName.text!.count > 0) {
}
}
private func configureTextFields () {
TextFieldName.delegate = self
}
/*
// MARK: - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// Get the new view controller using segue.destination.
// Pass the selected object to the new view controller.
}
*/
}
extension UIViewController: UITextFieldDelegate {
public func textFieldShouldReturn(_ textField: UITextField) -> Bool {
textField.resignFirstResponder()
return true
}
}
Maybe it sounds like a stupid question but I'm a beginner.​

Answer 1

#objc func buttonAction(_ : UIButton)
is a function and she must be outside of viewDidLoad, at the same level
class AddWorkoutController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
#objc func buttonAction(_ : UIButton) {
}
}
For me the best solution is to add your addButton in the storyboard with hidden property checked by default (select your button and then go to right panel > Show the attributes inspector > hidden property)
You must add func textFieldDidEndEditing(_ textField: UITextField) in your AddWorkoutController extension. Inside you can add your if (TextFieldName.text!.count > 0) and then change isHidden property of addButton (addButton.isHidden)
extension AddWorkoutController: UITextFieldDelegate {
public func textFieldShouldReturn(_ textField: UITextField) -> Bool {
textField.resignFirstResponder()
return true
}
func textFieldDidEndEditing(_ textField: UITextField) {
}
}
PS: Be carefull of your indentation for more lisibility and in general variable are written in camelCase You'll find some best practice here => https://github.com/raywenderlich/swift-style-guide