How to customize NSTextView in AppKit

Issue #320

Scrollable

• Putting an NSTextView Object in an NSScrollView
• Use xib then load

Embed image or NSTextAttachmentCellProtocol

• Select TextView
• Select Rich Text and Graphics
• Select Size Inspector -> Resizable and tick both Horizontally and Vertically

Customize

scrollView.drawsBackground = false
textView.drawsBackground = false
textView.string = "What's on your mind?"
textView.delegate = self
textView.selectedTextAttributes = [
    NSAttributedString.Key.backgroundColor: NSColor(hex: "414858"),
    NSAttributedString.Key.foregroundColor: NSColor(hex: "ACB2BE")
]

extension MainView: NSTextViewDelegate {
    func textViewDidChangeSelection(_ notification: Notification) {
        // Change text color again after image dragging
    }
}