how to set a background color in UIimage in swift programming

Question

I draw an image using drawInRect() method.

My rectangle is size of 120*120 and my image is 100 * 100.

How i can set a background color to my image in swift?

Answer 1

Swift 5, 4

If you need to draw the background of an image, for optimization and decorative purposes, you can draw the image in a specific way:

UIImage(named: "someImage")?.withBackground(color: .white)

---

Extension

extension UIImage {
  func withBackground(color: UIColor, opaque: Bool = true) -> UIImage {
    UIGraphicsBeginImageContextWithOptions(size, opaque, scale)
        
    guard let ctx = UIGraphicsGetCurrentContext(), let image = cgImage else { return self }
    defer { UIGraphicsEndImageContext() }
        
    let rect = CGRect(origin: .zero, size: size)
    ctx.setFillColor(color.cgColor)
    ctx.fill(rect)
    ctx.concatenate(CGAffineTransform(a: 1, b: 0, c: 0, d: -1, tx: 0, ty: size.height))
    ctx.draw(image, in: rect)
        
    return UIGraphicsGetImageFromCurrentImageContext() ?? self
  }
}