另一个与 Swift 2.2 兼容的不错的解决方案是以这种方式在UIImage中创建另一个构造函数：

public extension UIImage {
    public convenience init?(color: UIColor, size: CGSize = CGSize(width: 1, height: 1)) {
        let rect = CGRect(origin: .zero, size: size)
        UIGraphicsBeginImageContextWithOptions(rect.size, false, 0.0)
        color.setFill()
        UIRectFill(rect)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        guard let cgImage = image?.CGImage else { return nil }
        self.init(CGImage: cgImage)
    }  
}

这样，您可以通过以下方式创建自定义彩色图像：

let redImage = UIImage(color: .redColor())

或者，可以选择创建具有自定义尺寸的图像：

let redImage200x200 = UIImage(color: .redColor(), size: CGSize(width: 200, height: 200))

斯威夫特3.0

public extension UIImage {
  public convenience init?(color: UIColor, size: CGSize = CGSize(width: 1, height: 1)) {
    let rect = CGRect(origin: .zero, size: size)
    UIGraphicsBeginImageContextWithOptions(rect.size, false, 0.0)
    color.setFill()
    UIRectFill(rect)
    let image = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    guard let cgImage = image?.cgImage else { return nil }
    self.init(cgImage: cgImage)
  }
}