AttributedString.swift

import UIKit

struct AttributedString {
    private let _attributedString = NSMutableAttributedString()
    private let defaultAttributes: [NSAttributedStringKey: Any]

    var attributedString: NSAttributedString {
        return NSAttributedString(attributedString: _attributedString)
    }

    init(defaultAttributes: [NSAttributedStringKey: Any] = [:]) {
        self.defaultAttributes = defaultAttributes
    }

    func append<T: StringProtocol>(_ string: T, attributes: [NSAttributedStringKey: Any]? = nil) -> AttributedString {
        let mergedAttributes = attributes?
            .merging(defaultAttributes, uniquingKeysWith: { l, _ in l })

        _attributedString
            .append(NSAttributedString(string: string.description, attributes: mergedAttributes ?? defaultAttributes))

        return self
    }

    func append(attachment: NSTextAttachment) -> AttributedString {
        _attributedString
            .append(NSAttributedString(attachment: attachment))

        return self
    }

    func appendNewline() -> AttributedString {
        return append("\n")
    }

    func appendSpace() -> AttributedString {
        return append(" ")
    }
}