[Swift] iOS Implement Prefix Image String by using NSAttributedString

NSAttributedString+withPrefixImage.swift

//
//  NSAttributedString+withPrefixImage.swift
//
//  Created by 홍경표 on 2021/05/31.
//

import UIKit.UIImage

extension NSAttributedString {
    
    /// "AttributedString with a prefix image" maker
    /// - Parameters:
    ///   - prefixImage: a prefix image (will looks like an icon)
    ///   - text: some strings
    ///   - textAttributes: - [.font: UIFont.preferredFont(forTextStyle: .body), .foregroundColor: UIColor.black, ...]
    convenience init(prefixImage: UIImage?, text: String, textAttributes: [NSAttributedString.Key : Any]?) {
        let fullString = NSMutableAttributedString(
            string: text,
            // or string: "\( text)" for spacing
            attributes: textAttributes
        )
        
        let height = fullString.size().height
        if let prefixImage = prefixImage {
            let imagePrefix = NSAttributedString(
                attachment: NSTextAttachment().then {
                    $0.image = prefixImage
                    let ratio = prefixImage.size.width / prefixImage.size.height
                    $0.bounds = CGRect(x: $0.bounds.origin.x, y: $0.bounds.origin.y, width: ratio * height, height: height)
                }
            )
            fullString.insert(imagePrefix, at: 0)
        }
        
        self.init(attributedString: fullString)
    }
    
}