Remove alpha channel from png using Swift

remove_alpha_channel.swift

// Usage: swift remove_alpha_channel.swift filename.png

import Foundation
import CoreImage

let arguments = CommandLine.arguments
let filename = arguments[1]

let dataProvider = CGDataProvider(filename: filename)!
let cgImage = CGImage(pngDataProviderSource: dataProvider, decode: nil, shouldInterpolate: true, intent: .defaultIntent)!

let context = CGContext(data: nil, width: cgImage.width, height: cgImage.height, bitsPerComponent: cgImage.bitsPerComponent, bytesPerRow: cgImage.bytesPerRow, space: cgImage.colorSpace!, bitmapInfo: CGImageAlphaInfo.noneSkipLast.rawValue)!
context.draw(cgImage, in: CGRect(x: 0, y: 0, width: context.width, height: context.height))

let destination = CGImageDestinationCreateWithURL(URL(fileURLWithPath: filename) as CFURL, "public.png" as CFString, 1, nil)!
CGImageDestinationAddImage(destination, context.makeImage()!, nil)
CGImageDestinationFinalize(destination)