Instruction
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Displaying Writing Tools via UITextInteraction
Adding Writing Tools to your custom views requires two components. The first necessary component is the UITextInteraction. This class is not Writing Tools specific. It was released in iOS 13 and allows the end user to perform selection gestures on your custom text views.
Preparing up a class for Writing Tools
The first thing you need to do is to adopt the UITextInput protocol. Here is a custom text view. Notice that it is a UIView and it also implements the UITextInput protocol.
class CustomSkillsView: UIView, UITextInput{
private var textStorage = NSTextStorage()
private var layoutManager = NSLayoutManager()
private var textContainer = NSTextContainer()
var selectedTextRange: UITextRange?
var markedTextRange: UITextRange?
var markedTextStyle: [NSAttributedString.Key: Any]?
var inputDelegate: UITextInputDelegate?
var tokenizer: UITextInputTokenizer = UITextInputStringTokenizer()
Initializers and Configuration
The initializers for this class are fairly straight forward. They all use a setupInteraction() function to initialize the properties. Most importantly, these initializers setups a connection between the layout manager, the text storage. and the text container. This acts very much like a model-view-controller pattern.
private func setupInteraction() {
let textInteraction = UITextInteraction(for: .editable)
textInteraction.textInput = self
addInteraction(textInteraction)
textStorage.addLayoutManager(layoutManager)
layoutManager.addTextContainer(textContainer)
textContainer.lineFragmentPadding = 0
// Enable user interaction and set appearance
isUserInteractionEnabled = true
backgroundColor = .white
layer.borderColor = UIColor.gray.cgColor
layer.borderWidth = 1
// Initialize selectedTextRange
selectedTextRange = UITextRangeImpl(range: NSRange(location: 0, length: 0))
}
override var canBecomeFirstResponder: Bool {
return true
}
Enabling Writing Tools
There is a whole lot more to actually implement in your custom text view. You need to render the text on the screen, enable touch handling, as well as provide SwiftUI support. That’s a lot of code, but what about Writing Tools itself?
func replace(_ range: UITextRange, withText text: String) {
guard let range = range as? UITextRangeImpl else { return }
textStorage.replaceCharacters(in: range.nsRange, with: text)
setNeedsDisplay()
}