SwiftUI TextWithAttributedString

TextWithAttributedString.swift

public struct TextWithAttributedString: NSViewRepresentable {
    public typealias NSViewType = NSTextField
    
    public class Coordinator: NSObject, NSGestureRecognizerDelegate {
        let doubleTapCallback: () -> ()
        
        public init(doubleTapCallback: @escaping () -> ()) {
            self.doubleTapCallback = doubleTapCallback
        }
                
        @objc func doubleTapped(sender:NSClickGestureRecognizer) {
            self.doubleTapCallback()
        }
    }
    
    let attributedString: NSAttributedString
    let maximumNumberOfLines: Int
    let doubleTapCallback: () -> ()
    
    public init(attributedString: NSAttributedString, lineLimit: Int = 0, doubleTapCallback: @escaping () -> () = { }) {
        self.attributedString = attributedString
        self.maximumNumberOfLines = lineLimit
        self.doubleTapCallback = doubleTapCallback
    }
    
    public func makeCoordinator() -> TextWithAttributedString.Coordinator {
        print("DREW: about to construct coordinator in makeCoordinator.")
        return Coordinator(doubleTapCallback: self.doubleTapCallback)
    }
    
    public func makeNSView(context: Context) -> NSTextField {
        let tf = NSTextField(labelWithString: "")
        tf.maximumNumberOfLines = self.maximumNumberOfLines
        tf.alignment = .left
        tf.lineBreakMode = .byWordWrapping
        tf.autoresizesSubviews = true
        tf.drawsBackground = true
        tf.backgroundColor = NSColor.purple
        tf.setContentCompressionResistancePriority(NSLayoutConstraint.Priority(250), for: .horizontal)

        tf.cell?.truncatesLastVisibleLine = true // add the elipse on the last line that is truncated
        tf.autoresizingMask = [NSView.AutoresizingMask.width, NSView.AutoresizingMask.height]
        
        let tapGestureRecognizer = NSClickGestureRecognizer(target: context.coordinator, action: #selector(Coordinator.doubleTapped(sender:)))
        tapGestureRecognizer.numberOfClicksRequired = 2
        tapGestureRecognizer.delegate = context.coordinator
        tf.addGestureRecognizer(tapGestureRecognizer)
        
        return tf
    }
    
    public func updateNSView(_ nsView: NSTextField, context: Context) {
        nsView.attributedStringValue = attributedString
    }
    
    public func foregroundColor(_ color: NSColor) -> TextWithAttributedString {
        let mutableAttributedString = NSMutableAttributedString(attributedString: self.attributedString)
        let completeRange = NSRange(location: 0, length: mutableAttributedString.length)

        mutableAttributedString.addAttribute(NSAttributedString.Key.foregroundColor, value: color, range: completeRange)

        // NOTE: I have to do this because it turns out the Markdown library Down is introducing whitespace/newlines at the end of the content which is making it appear weird.
        return TextWithAttributedString(attributedString: mutableAttributedString.attributedStringByTrimmingCharacterSet(charSet: .whitespacesAndNewlines))
    }

    public func lineLimit(_ number: Int) -> TextWithAttributedString {
        return TextWithAttributedString(attributedString: self.attributedString, lineLimit: number)
    }
}