Cannot invoke 'addAnimations' with an argument list of type '(() -> (), delayFactor: Double)'

Question

I'm using UIViewPropertyAnimator to control the progress of multiple animations. I have a 2d array of UIView subclasses. I want to display all elements at each index at once. For some reason the compiler won't let me add new animations with a delay by using addAnimations(_:delayFactor:) method. Can someone tell me what am I doing wrong here?

// I'm creating a new viewAnimator without any animations. No problems here
        self.viewAnimator = UIViewPropertyAnimator(duration: self.frameDelay * Double(self.spillBubbles.count),
                                                   curve: .easeIn,
                                                   animations: {})


        for (index, views) in self.spillBubbles.enumerated() {

            views.forEach({ self.simulationView.addSubview($0) })

            // That's where the compiler error occurs 
            self.viewAnimator!.addAnimations({
                views.forEach({ self.simulationView.addSubview($0) })
            }, delayFactor: Double(index) / Double(self.spillBubbles.count))

        }

When I try to call .addAnimations I get the following message: Cannot invoke 'addAnimations' with an argument list of type '(() -> (), delayFactor: Double)'

What am I doing wrong here? The same closure called in the UIViewPropertyAnimator initializers works without any issues.

Answer 1

The error message is pretty clear. Just look at the docs if it isn't clear enough:

https://developer.apple.com/documentation/uikit/uiviewpropertyanimator/1648370-addanimations

The delayFactor needs to be a CGFloat, not a Double.