ImageMaker.m

// Create an image from an array of colors.
+ (UIImage *)createImageWithPixelData:(NSArray *)pixelData width:(int)width height:(int)height {
  CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

  // Add 1 for the alpha channel
  size_t numberOfComponents = CGColorSpaceGetNumberOfComponents(colorSpace) + 1;
  size_t bitsPerComponent = 8;
  size_t bytesPerPixel = (bitsPerComponent * numberOfComponents) / 8;
  size_t bytesPerRow = bytesPerPixel * width;
  uint8_t *rawData = (uint8_t*)calloc([pixelData count] * numberOfComponents, sizeof(uint8_t));

  CGContextRef context = CGBitmapContextCreate(rawData,
                                               width,
                                               height,
                                               bitsPerComponent,
                                               bytesPerRow,
                                               colorSpace,
                                               (CGBitmapInfo) kCGImageAlphaPremultipliedLast);

  CGColorSpaceRelease(colorSpace);

  int byteIndex = 0;
  for (int index = 0; index < [pixelData count]; index += 1) {
    CGFloat r, g, b, a;
    BOOL convert = [[pixelData objectAtIndex:index] getRed:&r green:&g blue:&b alpha:&a];
    if (!convert) {
      // TODO(cate): Handle this.
      NSLog(@"Failed, continue");
    }
    rawData[byteIndex] = r * 255;
    rawData[byteIndex + 1] = g * 255;
    rawData[byteIndex + 2] = b * 255;
    rawData[byteIndex + 3] = a * 255;
    byteIndex += 4;
  }

  CGImageRef imageRef = CGBitmapContextCreateImage(context);
  UIImage *newImage = [UIImage imageWithCGImage:imageRef];
  CGContextRelease(context);
  CGImageRelease(imageRef);
  return newImage;
}