iOS 通过颜色来生成一个纯色图片

- (UIImage *)buttonImageFromColor:(UIColor *)color{
CGRect rect = CGRectMake(0, 0, self.frame.size.width, self.frame.size.height);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [color CGColor]);
CGContextFillRect(context, rect);
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}