iOS 图片处理(截图，图片叠加(添加水印))

  //截图

UIGraphicsBeginImageContextWithOptions(CGSizeMake(640, 960), YES, 0);

[self.layer renderInContext:UIGraphicsGetCurrentContext()];

UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

CGImageRef imageRef = viewImage.CGImage;

CGRect rect =CGRectMake(100, 100, 200, 300);//这里可以设置想要截图的区域

CGImageRef imageRefRect =CGImageCreateWithImageInRect(imageRef, rect);

UIImage *sendImage = [[UIImage alloc] initWithCGImage:imageRefRect];

NSData *imageViewData = UIImagePNGRepresentation(sendImage);

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

NSString *documentsDirectory = [paths objectAtIndex:0];

NSString *savedImagePath = [documentsDirectory stringByAppendingPathComponent:@"result.png"];

    NSLog(@"%@", savedImagePath);

[imageViewData writeToFile:savedImagePath atomically:YES];

CGImageRelease(imageRefRect);

注：iOS7以后renderInContext：由drawViewHierarchyInRect：afterScreenUpdates：替代，可以判断。

同时可以截取整个scrollview得大小

- (UIImage *)imageViewFromScreen:(UIScrollView *)scrollView

{

    UIImage* image = nil;

    UIGraphicsBeginImageContext(scrollView.contentSize);

    {

        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()];

        image = UIGraphicsGetImageFromCurrentImageContext();

        

        scrollView.contentOffset = savedContentOffset;

        scrollView.frame = savedFrame;

    }

    UIGraphicsEndImageContext();

    

    if (image != nil) {

        return image;

    }

    return nil;

}

图片叠加，比如：

// 添加logo水印

- (UIImage *)addlogoImage:(UIImage *)resizedImage

{

    UIGraphicsBeginImageContext(resizedImage.size);

    [resizedImage drawInRect:CGRectMake(0, 0, resizedImage.size.width, resizedImage.size.height)];

    

    UIImage *maskImage  = [UIImage imageNamed:@"dzh_logo.png"];

    

    [maskImage drawInRect:CGRectMake((resizedImage.size.width - maskImage.size.width)/2,

                                     (resizedImage.size.height - maskImage.size.height)/2,

                                     maskImage.size.width,

                                     maskImage.size.height)];

    

    UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return resultingImage;

 

}