Shorthand for creating empty (black) UIImage.

UIImage+Placeholder.swift

import UIKit

extension UIImage {
    static func placeholder(size: CGSize) -> UIImage {
        UIGraphicsBeginImageContext(size)
        
        let context = UIGraphicsGetCurrentContext()
        CGContextSetRGBFillColor(context, 0, 0, 0, 1)
        CGContextFillRect(context, CGRectMake(0, 0, size.width, size.height))
        
        let image = UIGraphicsGetImageFromCurrentImageContext()
        
        UIGraphicsEndImageContext()
        
        return image
    }
}