Liquid Blob effect with SwiftUI

LiquidBlobs.swift

//
//  ContentView.swift
//  LiquidCircles
//
//  Created by Paul Stamatiou on 10/10/22.
//

import SwiftUI

struct ContentView: View {
    @State var animate: Bool = false

    var body: some View {
        VStack {
            Spacer()
            
            Canvas { context, size in
                // The real magic lies in these two filters. 
                // This is an approach common with SVG using feGaussianBlur and feColorMatrix
            
                // https://developer.apple.com/documentation/swiftui/graphicscontext/filter/alphathreshold(min:max:color:)?changes=_7_3_5&language=objc
                // Returns a filter that replaces each pixel with alpha components within a range by a constant color, or transparency otherwise.
                context.addFilter(.alphaThreshold(min: 0.5, color: .black))
                
                // Gaussian blur 
                context.addFilter(.blur(radius: 15))
                
                // drawLayer creates a new transparency layer that you can draw into
                // the above filters won't work without drawing the swiftui symbols into their single layer added to the main context
                context.drawLayer { ctx in
                    // access the passed in symbols using their .tag() id 
                    let circle0 = ctx.resolveSymbol(id: 0)!
                    let circle1 = ctx.resolveSymbol(id: 1)!
                    
                    ctx.draw(circle0, at: CGPoint(x: 131, y: 50))
                    ctx.draw(circle1, at: CGPoint(x: 262, y: 50))
                }
                
            } symbols: {
                // symbols is how you can tell canvas to accept a regular SwiftUI view to work with
                // required to .tag() so you get an id to resolve the symbol inside canvas 
                Circle()
                    .fill(.black)
                    .frame(width: 90, height: 90)
                    .offset(x: animate ? 66 : -40)
                    .tag(0)
                
                Circle()
                    .fill(.black)
                    .frame(width: 90, height: 90)
                    .offset(x: animate ? -66 : 40)
                    .tag(1)
            }
            .animation(.easeInOut(duration: 2).repeatForever(autoreverses: true), value: animate)
            .frame(height: 100)
            
            Spacer()
        }
        .onAppear { animate = true }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

Thanks a lot for this gist 😊
It was not animating for me so I had to update the state variable from inside Task{}

.task {
      animate = true
  }