图片合成

-(UIImage *)addImage:(UIImage *)image1 toImage:(UIImage *)image2 {
UIGraphicsBeginImageContext(image1.size);
// Draw image1
[image1 drawInRect:CGRectMake(0, 0, image1.size.width, image1.size.height)];
// Draw image2
[image2 drawInRect:CGRectMake(0, 0, image2.size.width, image2.size.height)];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return resultingImage;
}

图片拼接（左右拼接）

-(UIImage *) combine:(UIImage *)leftImage :(UIImage )rightImage {
CGFloat width = leftImage.size.width ;
CGFloat height = leftImage.size.height;
CGSize offScreenSize = CGSizeMake(width, height);
UIGraphicsBeginImageContext(offScreenSize);
CGRect rect = CGRectMake(0, 0, width, height);
[leftImage drawInRect:rect];
rect.origin.y += height;
[rightImage drawInRect:rect];
UIImage imagez = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return imagez;
}

图片拼接（上下拼接，以第一张图片的宽度为主）

-(UIImage *)combine:(UIImage *)oneImage otherImage:(UIImage *)otherImage {
//计算画布大小
CGFloat width = oneImage.size.width;
CGFloat height = oneImage.size.height + otherImage.size.height+30;
CGSize resultSize = CGSizeMake(width, height);
UIGraphicsBeginImageContextWithOptions(resultSize,nil, 0.0);
//放第一个图片
CGRect oneRect = CGRectMake(0, 0, resultSize.width, oneImage.size.height);
[oneImage drawInRect:oneRect];
//放第二个图片
CGRect otherRect = CGRectMake(0, oneRect.size.height, resultSize.width, otherImage.size.height+30);
[otherImage drawInRect:otherRect];
UIImage *resultImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return resultImage;
}

通过颜色来生成一个纯色图片

-(UIImage *)buttonImageFromColor:(UIColor *)color{
CGRect rect = CGRectMake(0, 0, SCREEN_WIDTH, 1);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [color CGColor]);
CGContextFillRect(context, rect);
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}

tableView截图

-(UIImage *)getTableViewimage:(UITableView )tableview{
UIImage viewImage = nil;
UITableView *scrollView = tableview;
UIGraphicsBeginImageContextWithOptions(scrollView.contentSize, scrollView.opaque, 0.0);
{
CGPoint savedContentOffset = scrollView.contentOffset;
CGRect savedFrame = scrollView.frame;
scrollView.contentOffset = CGPointZero;
scrollView.frame = CGRectMake(0, 0, scrollView.contentSize.width, scrollView.contentSize.height);
[scrollView.layer renderInContext: UIGraphicsGetCurrentContext()];
viewImage = UIGraphicsGetImageFromCurrentImageContext();
scrollView.contentOffset = savedContentOffset;
scrollView.frame = savedFrame;
}
UIGraphicsEndImageContext();
return viewImage;
}