Animating Text in Swift UI

Question

How would it be possible to animate Text or TextField views from Swift UI?

By animation I mean, that when the text changes it will \"count up\

Answer 1

You can use a CADisplayLink in a BindableObject to create a timer that updates your text during the animation. Gist

class CADisplayLinkBinding: NSObject, BindableObject {

    let didChange = PassthroughSubject()
    private(set) var progress: Double = 0.0

    private(set) var startTime: CFTimeInterval = 0.0
    private(set) var duration: CFTimeInterval = 0.0
    private(set) lazy var displayLink: CADisplayLink = {
        let link = CADisplayLink(target: self, selector: #selector(tick))
        link.add(to: .main, forMode: .common)
        link.isPaused = true
        return link
    }()

    func run(for duration: CFTimeInterval) {
        let now = CACurrentMediaTime()
        self.progress = 0.0
        self.startTime = now
        self.duration = duration
        self.displayLink.isPaused = false
    }

    @objc private func tick() {
        let elapsed = CACurrentMediaTime() - self.startTime
        self.progress = min(1.0, elapsed / self.duration)
        self.displayLink.isPaused = self.progress >= 1.0
            self.didChange.send(self)
    }

    deinit {
        self.displayLink.invalidate()
    }

}

And then to use it:

@ObjectBinding var displayLink = CADisplayLinkBinding()

var body: some View {
    Text("\(Int(self.displayLink.progress*100))")
        .onAppear {
            self.displayLink.run(for: 10.0)
    }
}