TokenTextField.swift

//

import UIKit
import UniformTypeIdentifiers

protocol TokenTextFieldDelegate: AnyObject {
    func tokenizedTextField(_ sender: TokenTextField, didTapTokenView: UIView)
}

final class TokenTextField: UITextView {
    private static let tokenFileType = UTType.plainText.identifier
    
    enum Model {
        case token(String)
        case text(String)
    }
    
    var data: [Model] = [] {
        didSet {
            let attributedText = attributedText(for: data)
            self.attributedText = attributedText
        }
    }
    
    var tokenDelegate: TokenTextFieldDelegate?
    
    override init(frame: CGRect, textContainer: NSTextContainer?) {
        super.init(frame: frame, textContainer: textContainer)
        NSTextAttachment.registerViewProviderClass(TokenAttachmentViewProvider.self, forFileType: Self.tokenFileType)
    }
    
    required init?(coder: NSCoder) { fatalError() }
    
    private func attributedText(for data: [Model]) -> NSAttributedString {
        let result = NSMutableAttributedString()
        data.forEach { data in
            switch data {
            case .token(let value):
                let attachment = NSTextAttachment(data: value.data(using: .utf8), ofType: Self.tokenFileType)
                let substring = NSMutableAttributedString(attachment: attachment)
                result.append(substring)
            case .text(let value):
                result.append(NSAttributedString(string: value, attributes: [
                    .font: UIFont.preferredFont(forTextStyle: .body),
                    .foregroundColor: UIColor.label
                ]))
            }
        }
        return result
    }
}


#Preview {
    final class MyDelegate: NSObject, TokenTextFieldDelegate, UITextViewDelegate {
        func tokenizedTextField(_ sender: TokenTextField, didTapTokenView token: UIView) {
            token.layer.add(shake(), forKey: "shake")
        }
        
        private func shake() -> CAAnimation {
            let animation = CAKeyframeAnimation(keyPath: "position.x")
            animation.values = [0, 10, -10, 10, 0]
            animation.keyTimes = [0, 0.1, 0.3, 0.5, 0.7, 0.9, 1]
            animation.duration = 0.6
            animation.isAdditive = true
            animation.timingFunctions = [
                CAMediaTimingFunction(name: .linear),
                CAMediaTimingFunction(name: .easeInEaseOut),
                CAMediaTimingFunction(name: .easeInEaseOut),
                CAMediaTimingFunction(name: .easeInEaseOut)
            ]
            
            return animation
        }
    }
    
    let textView = TokenTextField(frame: CGRect(x: 0, y: 0, width: 250, height: 120))
    textView.data = [
        .text("And it's a "),
        .token("good"),
        .text(" day for shinin' your shoes\n"),
        .text("And it's a good day for losin' the blues\n"),
        .text("Everything to "),
        .token("gain"),
        .text(" and nothing to lose\n"),
        .text("A good day from morning 'til night"),
    ]
    let delegate = MyDelegate()
    textView.tokenDelegate = delegate
    textView.delegate = delegate
    textView.layer.cornerRadius = 8
    
    let blurView = UIVisualEffectView(effect: UIBlurEffect(style: .systemThickMaterial))
    blurView.frame = textView.bounds
    blurView.alpha = 0.5
    textView.addSubview(blurView)
    textView.sendSubviewToBack(blurView)
    
    let container = UIView(frame: UIScreen.main.bounds)
    container.addSubview(textView)
    textView.center = container.center
    return container
}

class TokenAttachmentViewProvider: NSTextAttachmentViewProvider {
    override init(textAttachment: NSTextAttachment, parentView: UIView?, textLayoutManager: NSTextLayoutManager?, location: any NSTextLocation) {
        super.init(textAttachment: textAttachment, parentView: parentView, textLayoutManager: textLayoutManager, location: location)
        guard let data = textAttachment.contents, let token = String(bytes: data, encoding: .utf8) else {
            return
        }
        tracksTextAttachmentViewBounds = true
        
        let button = UIButton(type: .custom)
        button.setTitle(token, for: .normal)
        button.configuration = .borderedProminent()
        button.addAction(UIAction(handler: { [weak self, weak button] _ in
            guard let self,
                    let button,
                    let textView = textView(for: parentView) else { return }
            textView.tokenDelegate?.tokenizedTextField(textView, didTapTokenView: button)
        }), for: .touchUpInside)
        button.sizeToFit()
        let container = UIView(frame: button.bounds)
        button.frame.origin.y += 10
        container.addSubview(button)
        self.view = container
    }
    
    override func attachmentBounds(for attributes: [NSAttributedString.Key : Any], location: any NSTextLocation, textContainer: NSTextContainer?, proposedLineFragment: CGRect, position: CGPoint) -> CGRect {
        return self.view?.bounds ?? .zero
    }
    
    private func textView(for view: UIView?) -> TokenTextField? {
        var current: UIView? = view
        while current != nil {
            if let textView = current as? TokenTextField {
                return textView
            }
            current = current?.superview
        }
        return nil
    }
}