sharing.swift

import SwiftUI

struct ContentView: View {
  let size: CGSize = CGSize(width: 200, height: 200)
  @State private var positions = [CGRect]()
  @State private var counter = 0

  var body: some View {
    ZStack {
      ForEach(positions, id: \.self) { position in
        Image(systemName: "gift")
          .position(x: position.midX, y: position.midY)
          .rotationEffect(Angle(degrees: makeRotationAngle()))
          .scaleEffect(.random(in: 0.7...1.5))
          .foregroundColor(.secondary)
      }
    }
    .clipped()
    .frame(width: 200, height: 200)
    .background(.white)
    .cornerRadius(16)
    .frame(maxWidth: .infinity, maxHeight: .infinity)
    .background(.black)
    .ignoresSafeArea()
    .onAppear {
      makePositions()
    }
  }

  func makePositions() {
    while positions.count < 50 {
      let randomPosition = makePosition(in: size)
      print(randomPosition)
      if !containsPosition(randomPosition) {
        positions.append(randomPosition)
        print("Append!")
        counter += 1
        print(counter)
      }
    }
  }

  func containsPosition(_ position: CGRect) -> Bool {
    positions.contains { $0.intersects(position) }
  }

  func makePosition(in size: CGSize) -> CGRect {
    let xPos = Int.random(in: 0..<Int(size.width))
    let yPos = Int.random(in: 0..<Int(size.height))
    return CGRect(x: CGFloat(xPos), y: CGFloat(yPos), width: 10, height: 10)
  }

  func makeRotationAngle() -> Double {
    Double.random(in: -15...15)
  }
}

extension CGRect: Hashable {
  public func hash(into hasher: inout Hasher) {
    hasher.combine(self.midX)
    hasher.combine(self.midY)
  }
}

struct SizePreferenceKey: PreferenceKey {
  static var defaultValue: CGSize = .zero
  static func reduce(value: inout CGSize, nextValue: () -> CGSize) {}
}

extension View {
  func readSize(onChange: @escaping (CGSize) -> Void) -> some View {
    background(
      GeometryReader { geo in
        Color.clear
          .preference(key: SizePreferenceKey.self, value: geo.size)
      }
    )
    .onPreferenceChange(SizePreferenceKey.self, perform: onChange)
  }
}