defer-draw.swift

    let scaledImage: UIImage
    do {
        UIGraphicsBeginImageContextWithOptions(size, false, 0.0)
        defer {
            UIGraphicsEndImageContext()
        }
        // Fill background
        UIColor.blackColor().setFill(); UIRectFill(CGRect(origin: .zero, size: size))
        
        // Draw scaled image
        let drawingRect: CGRect = CGRect(
            origin: drawingOrigin,
            size: CGSize(width: scaledWidth, height: scaledHeight))
        image.drawInRect(drawingRect)
        
        // Fetch image
        scaledImage = UIGraphicsGetImageFromCurrentImageContext()!
    }