인증번호(OneTime Code) 입력 뷰

OneTimeCodeTextField.swift

//
//  OneTimeCodeTextField.swift
//
//  Created by 홍경표 on 2021/05/13.
//

import UIKit

final class OneTimeCodeTextField: UITextField {

    let slotCount: Int
    private var digitLabels: [UILabel] = []
    
    init(slotCount: Int) {
        self.slotCount = slotCount
        super.init(frame: .zero)
        configure()
    }
    required init?(coder: NSCoder) {
        fatalError("NO WAY")
    }
    
    private func configure() {
        self.tintColor = .clear
        self.textColor = .clear
        self.textAlignment = .center
        self.keyboardType = .numberPad
        if #available(iOS 12.0, *) {
            self.textContentType = .oneTimeCode
        }
        
        self.addTarget(self, action: #selector(textDidChange), for: .editingChanged)
        
        let tapRecognizer = UITapGestureRecognizer()
        tapRecognizer.addTarget(self, action: #selector(becomeFirstResponder))
        self.addGestureRecognizer(tapRecognizer)
        
        let labelsStackView = UIStackView().then {
            $0.axis = .horizontal
            $0.distribution = .fillEqually
            $0.alignment = .fill
            $0.spacing = 8
        }
        
        for _ in 0..<slotCount {
            let label = UILabel().then {
                $0.textAlignment = .center
                $0.font = .preferredFont(forTextStyle: .largeTitle)
                $0.adjustsFontSizeToFitWidth = true
                $0.text = " "
            }
            labelsStackView.addArrangedSubview(label)
            digitLabels.append(label)
        }
        self.addSubview(labelsStackView)
        labelsStackView.snp.makeConstraints {
            $0.edges.equalToSuperview()
        }
        
        for i in 0..<slotCount {
            let bottomLine = UIView()
            bottomLine.backgroundColor = UIColor(named: "c006")
            digitLabels[i].addSubview(bottomLine)
            bottomLine.snp.makeConstraints {
                $0.height.equalTo(2)
                $0.leading.trailing.bottom.equalToSuperview()
            }
        }
    }
    
    @objc private func textDidChange() {
        guard let text = self.text else { return }
        guard text.count <= slotCount else {
            self.text = text.prefix(slotCount).description
            return
        }
        for i in 0..<slotCount {
            if i < text.count {
                digitLabels[i].text = String(text[text.index(text.startIndex, offsetBy: i)])
            } else {
                digitLabels[i].text = " "
            }
        }
    }
    
}