Is there joinWithSeparator for attributed strings

Question

Array of strings can be joined together with specific separator using joinWithSeparator method.

let st = [ "apple", "pie", "potato" ]
st.joinWithSeparator(", ")

As a result we will have "apple, pie, potato".

What if I have attributed strings inside my array? Is there easy way to combine them into one big attributed string?

Answer 1

Swift 5:

import Foundation

extension Sequence where Iterator.Element == NSAttributedString {
    func joined(with separator: NSAttributedString) -> NSAttributedString {
        return self.reduce(NSMutableAttributedString()) {
            (r, e) in
            if r.length > 0 {
                r.append(separator)
            }
            r.append(e)
            return r
        }
    }

    func joined(with separator: String = "") -> NSAttributedString {
        return self.joined(with: NSAttributedString(string: separator))
    }
}

Swift 4:

import Foundation

extension SequenceType where Generator.Element: NSAttributedString {
    func joinWithSeparator(separator: NSAttributedString) -> NSAttributedString {
        var isFirst = true
        return self.reduce(NSMutableAttributedString()) {
            (r, e) in
            if isFirst {
                isFirst = false
            } else {
                r.appendAttributedString(separator)
            }
            r.appendAttributedString(e)
            return r
        }
    }

    func joinWithSeparator(separator: String) -> NSAttributedString {
        return joinWithSeparator(NSAttributedString(string: separator))
    }
}

Answer 2

Took this solution from SwifterSwift, it's similar to the other ones:

public extension Array where Element: NSAttributedString {
    func joined(separator: NSAttributedString) -> NSAttributedString {
        guard let firstElement = first else { return NSMutableAttributedString(string: "") }
        return dropFirst().reduce(into: NSMutableAttributedString(attributedString: firstElement)) { result, element in
            result.append(separator)
            result.append(element)
        }
    }

    func joined(separator: String) -> NSAttributedString {
        guard let firstElement = first else { return NSMutableAttributedString(string: "") }
        let attributedStringSeparator = NSAttributedString(string: separator)
        return dropFirst().reduce(into: NSMutableAttributedString(attributedString: firstElement)) { result, element in
            result.append(attributedStringSeparator)
            result.append(element)
        }
    }
}