Add selectable text feature

Changelog-Added: Added the ability to select text on posts
Closes: #639

damus/Components/SelectableText.swift

@@ -0,0 +1,96 @@
+//
+//  SelectableText.swift
+//  damus
+//
+//  Created by Oleg Abalonski on 2/16/23.
+//
+
+import UIKit
+import SwiftUI
+
+struct SelectableText: View {
+    
+    let attributedString: AttributedString
+    
+    @State private var selectedTextHeight: CGFloat = .zero
+    @State private var selectedTextWidth: CGFloat = .zero
+    
+    var body: some View {
+        GeometryReader { geo in
+            TextViewRepresentable(
+                attributedString: attributedString,
+                textColor: UIColor.label,
+                font: UIFont.preferredFont(forTextStyle: .title2),
+                fixedWidth: selectedTextWidth,
+                height: $selectedTextHeight
+            )
+            .onAppear {
+                self.selectedTextWidth = geo.size.width
+            }
+            .onChange(of: geo.size) { newSize in
+                self.selectedTextWidth = newSize.width
+            }
+        }
+        .frame(height: selectedTextHeight)
+    }
+}
+
+ fileprivate struct TextViewRepresentable: UIViewRepresentable {
+
+    let attributedString: AttributedString
+    let textColor: UIColor
+    let font: UIFont
+    let fixedWidth: CGFloat
+
+    @Binding var height: CGFloat
+
+    func makeUIView(context: UIViewRepresentableContext<Self>) -> UITextView {
+        let view = UITextView()
+        view.isEditable = false
+        view.dataDetectorTypes = .all
+        view.isSelectable = true
+        view.textContainer.lineFragmentPadding = 0
+        view.textContainerInset = .zero
+        return view
+    }
+
+    func updateUIView(_ uiView: UITextView, context: UIViewRepresentableContext<Self>) {
+        let mutableAttributedString = createNSAttributedString()
+        uiView.attributedText = mutableAttributedString
+
+        let newHeight = mutableAttributedString.height(containerWidth: fixedWidth)
+
+        DispatchQueue.main.async {
+            height = newHeight
+        }
+    }
+
+    func createNSAttributedString() -> NSMutableAttributedString {
+        let mutableAttributedString = NSMutableAttributedString(attributedString)
+        let myAttribute = [
+            NSAttributedString.Key.font: font,
+            NSAttributedString.Key.foregroundColor: textColor
+        ]
+
+        mutableAttributedString.addAttributes(
+            myAttribute,
+            range: NSRange.init(location: 0, length: mutableAttributedString.length)
+        )
+
+        return mutableAttributedString
+    }
+}
+
+fileprivate extension NSAttributedString {
+
+    func height(containerWidth: CGFloat) -> CGFloat {
+
+        let rect = self.boundingRect(
+            with: CGSize.init(width: containerWidth, height: CGFloat.greatestFiniteMagnitude),
+            options: [.usesLineFragmentOrigin, .usesFontLeading],
+            context: nil
+        )
+
+        return ceil(rect.size.height)
+    }
+}