给出颜色生成图片
- (UIImage *) createImageWithColor: (UIColor *) color
{
CGRect rect = CGRectMake(0.0f,0.0f,1.0f,1.0f);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context =UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [colorCGColor]);
CGContextFillRect(context, rect);
UIImage *theImage =UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return theImage;
}