Animate Single Character in String Swift - swift

Question

How can we animate a single character within a string? ie: I have the string: "Hey 👋". I would like to animate the emoji by setting it to rotate back and forth so it looks like it's waving.
To detect the emoji, I'm using:
extension String {
// Not needed anymore in swift 4.2 and later, using `.count` will give you the correct result
var glyphCount: Int {
let richText = NSAttributedString(string: self)
let line = CTLineCreateWithAttributedString(richText)
return CTLineGetGlyphCount(line)
}
var isSingleEmoji: Bool {
return glyphCount == 1 && containsEmoji
}
var containsEmoji: Bool {
return unicodeScalars.contains { $0.isEmoji }
}
I'm using the emoji code here: Find out if Character in String is emoji?.
I'm unsure how to set up the animation

Answer 1

I've very slightly modified this excellent answer by Rob in this post.
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
animateEmojiBackandForth("👋")
}
func animateEmojiBackandForth (_ searchText: String) {
let beginning = textView.beginningOfDocument
guard let string = textView.text,
let range = string.range(of: searchText),
let start = textView.position(from: beginning, offset: string.distance(from: string.startIndex, to: range.lowerBound)),
let end = textView.position(from: beginning, offset: string.distance(from: string.startIndex, to: range.upperBound)),
let textRange = textView.textRange(from: start, to: end)
else { return }
textView.selectionRects(for: textRange)
.forEach { selectionRect in
guard let snapshotView = textView.resizableSnapshotView(from: selectionRect.rect, afterScreenUpdates: false, withCapInsets: .zero) else { return }
snapshotView.frame = view.convert(selectionRect.rect, from: textView)
view.addSubview(snapshotView)
UIView.animate(withDuration: 1, delay: 0, options: .autoreverse, animations: {
snapshotView.transform = CGAffineTransform(rotationAngle: CGFloat( CGFloat.pi / 4))
}, completion: { _ in
snapshotView.removeFromSuperview()
})
}
}
You can modify the duration of the animation and the angle of the "wave" if you wish. I hope this was helpful!