UIImage noise animation generator

UIImage+noiseAnimation.swift

import UIKit

public extension UIImage {
    static var noiseAnimation: UIImage = {
        makeNoiseAnimation(
            size: CGSize(width: 226, height: 168),
            framesCount: 4,
            magnitude: 0.5,
            duration: 0.2
        ) ?? UIImage()
    }()
}

// MARK: - Implementation

private func makeNoiseAnimation(
    size: CGSize,
    framesCount: Int,
    magnitude: Double,
    duration: TimeInterval
) -> UIImage? {
    UIImage.animatedImage(
        with: (0..<framesCount).compactMap { _ in
            makeNoiseImage(size: size, magnitude: magnitude)
        },
        duration: duration
    )
}

private func makeNoiseImage(size: CGSize, magnitude: Double) -> UIImage? {
    let width = Int(size.width)
    let height = Int(size.height)
    let bytesPerPixel = 4
    let bytesPerRow = width * bytesPerPixel
    let imageData = UnsafeMutablePointer<UInt8>.allocate(
        capacity: width * height * bytesPerPixel
    )

    for y in 0..<height {
        for x in 0..<width {
            let offset = y * bytesPerRow + x * bytesPerPixel
            let intensity = UInt8(Double(arc4random() % 256) * magnitude)
            imageData[offset] = UInt8(intensity) // Red
            imageData[offset + 1] = UInt8(intensity) // Green
            imageData[offset + 2] = UInt8(intensity) // Blue
            imageData[offset + 3] = 255 // Alpha
        }
    }

    let bitmapInfo = CGImageAlphaInfo.premultipliedLast.rawValue | CGBitmapInfo.byteOrder32Big.rawValue
    guard let context = CGContext(data: imageData, width: width, height: height, bitsPerComponent: 8, bytesPerRow: bytesPerRow, space: CGColorSpaceCreateDeviceRGB(), bitmapInfo: bitmapInfo) else {
        return nil
    }

    guard let cgImage = context.makeImage() else {
        return nil
    }

    return UIImage(cgImage: cgImage)
}