Struggling with referencing a variable (Swift) - ios

Question

Background:
I'm trying to animate a wave using BAFluidView. My goal is pretty simple: start the animation when a button is tapped, stop it when it is tapped again. The pod (linked above) provides all of the code to manage this.
Let it be known, I'm new to this. Help me learn, please!
My struggle:
I need to create a view for this wave. I put it into a function called "WaveContainer." Here's what that looks like:
func WaveAnimation() {
let wave = BAFluidView(frame: self.view.frame, startElevation: 0.02)!
wave.maxAmplitude = 10
wave.minAmplitude = 8
wave.fillDuration = 50
wave.fill(to: 0.95)
wave.fillAutoReverse = false
wave.fillColor = UIColor.blue
waveView.addSubview(wave)
}
I then called this in the ViewDidAppear function. Of course, it works! I can see the wave, and it's waving. Nice.
Of course, I can't call the wave constant anywhere else, though! If I want to stop / start the wave on a button press, for example?
If I try to move the wave constant out of this function into ViewDidLoad or ViewDidAppear, I can't access the ...self.view.frame, and the wave won't show up on the screen.
My asks:
How should I structure this code so that I can reference the wave constant from several different functions?
How should I reference the view for the wave constant when I'm not within ViewDidLoad or some other view-based function?
Thank you SO MUCH for your help!
My Code:
import UIKit
import BAFluidView
class ViewController: UIViewController {
// OUTLETS:
#IBOutlet weak var waveView: UIView!
// ACTIONS:
#IBAction func WaveButton(_ sender: UIButton) {
// If the user taps this button and the waveHasStarted variable is equal to false, flip it to true.
if waveHasStarted == false {
print("Start the wave with a press.")
startWave = true
waveHasStarted = true
waveHasBeenStopped = false
} else {
print("Stop the wave with a press.")
startWave = false
waveHasStarted = false
waveHasBeenStopped = true
}
}
// VARIABLES:
var waveHasStarted = false
var startWave = false
var waveHasBeenStopped = true
override func viewDidLoad() {
super.viewDidLoad()
}
override func viewDidAppear(_ animated: Bool) {}
// FUNCTIONS:
func WaveAnimation() {
let wave = BAFluidView(frame: self.view.frame, startElevation: 0.02)!
wave.maxAmplitude = 10
wave.minAmplitude = 8
wave.fillDuration = 50
wave.fill(to: 0.95)
wave.fillAutoReverse = false
wave.fillColor = UIColor.blue
// If the variable above has been flipped to "true," start the animation...
if startWave == true {
print("Start that wave animation")
wave.startAnimation()
} else {
// If not, stop it or do nothing.
print("Stop that wave animation")
wave.stopAnimation()
wave.keepStationary()
}
waveView.addSubview(wave)
}
}

Answer 1

Use lazy initialization and get the class level access,
lazy var fluidView: BAFluidView = {
let wave = BAFluidView(frame: self.view.frame, startElevation: 0.02)!
wave.maxAmplitude = 10
wave.minAmplitude = 8
wave.fillDuration = 50
wave.fill(to: 0.95)
wave.fillAutoReverse = false
wave.fillColor = UIColor.blue
return wave
}()
Now you can add, start and stop the animation anywhere as,
waveView.addSubview(fluidView)
fluidView.startAnimation()
fluidView.stopAnimation()