Extension to UIImage which returns an image filled with given solid color and given size.

UIImage+Color.swift

import UIKit

extension UIImage {
    
    static func imageWithColor(color: UIColor, size: CGSize = CGSize(width: 1, height: 1)) -> UIImage? {
        
        UIGraphicsBeginImageContext(size)
        if let context = UIGraphicsGetCurrentContext() {
            context.setFillColor(color.cgColor)
            context.fill(CGRect(origin: .zero, size: size))
        }
        
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        
        return image
    }
}