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I'm new to programming - but I've made strides learning Swift for iOS in the last two months. I'm making a simple typing game - and the way I've structured my project is that I have a hidden UITextView that detects the character pressed by the player, and I match that character string with a visible UITextView's character string.

What I'm looking to do now is to add some sort of animation - I'd like the individual letters to fade in/out

I've created an attributed string, added it to a UITextView, and I just can't figure out a way to animate a specific range in the string. I've tried using something along the lines of this:

            UIView.animateWithDuration(1, delay: 0.5, options: .CurveEaseOut, animations: {

                self.stringForPlayer.addAttribute(

                    NSForegroundColorAttributeName,

                    value: UIColor.greenColor(),

                    range: NSRange(location: self.rangeOfText, length: 1))

                self.textViewForPlayer.attributedText = self.textForPlayer

                }, completion: { finished in

                    println("FINISHED")}

            )

with no luck. I figure maybe UIView animations are only on the view object itself and can't be used on the attributed string. Any ideas or even workarounds to make this happen? Any help is appreciated, thanks a lot!

You can use transition(with:...) to do an animation. In this case, fading the word ipsum into green. E.g. in Swift 3 and later:

let range = (playerTextView.text as NSString).range(of: "ipsum")

let string = playerTextView.attributedText.mutableCopy() as! NSMutableAttributedString

string.addAttribute(.foregroundColor, value: UIColor.green, range: range)



UIView.transition(with: playerTextView, duration: 1.0, options: .transitionCrossDissolve, animations: {

    self.playerTextView.attributedText = string

})

To have the text shrink and grow during this animation is a whole different ball of wax because simple attempts to change the size of the text will cause the rest of the text view to be re laid out, which I am sure is not your intent.

In that case, I might take a snapshot of that portion of the text view, lay that snapshot over the text view, animate the resizing and transformation. And all of that assumes that what you're transforming it to at the end of the animation is exactly the same size as it was before (otherwise you have a complicated question of what to do with the rest of the text during the animation).

This is going to be a lot of work to achieve a particular animation. I'd ask whether you could accomplish the desired effect more simply other ways (e.g. nested animations, one that fades the text color to clear and then fade it to the new color making it achieve a bit of the "disappear and reappear" feel). That makes the transformation more notable while not getting lost in a rats nest of animation code.

If you wanted to fade it to clear before fading it to the desired color (making it "pop" a little more), you could use the completion block:

let range = (playerTextView.text as NSString).range(of: "ipsum")

let string = playerTextView.attributedText.mutableCopy() as! NSMutableAttributedString

string.addAttribute(.foregroundColor, value: UIColor.clear, range: range)



UIView.transition(with: playerTextView, duration: 0.25, options: .transitionCrossDissolve, animations: {

    self.playerTextView.attributedText = string

}, completion: { _ in

    string.addAttribute(.foregroundColor, value: UIColor.green, range: range)

    UIView.transition(with: self.playerTextView, duration: 0.25, options: .transitionCrossDissolve, animations: {

        self.playerTextView.attributedText = string

    })

})

For previous versions of Swift, see prior revision of this answer.