以下是我目前的代码.我想截取屏幕截图,同时使用iOS6 Facebook功能导出到Facebook.

- (IBAction)export1:(id)sender{

NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];
[self.tableView scrollToRowAtIndexPath:indexPath
                      atScrollPosition:UITableViewScrollPositionTop
                              animated:YES];
exporting.hidden=YES;

CGSize imageSize = [[UIScreen mainScreen] bounds].size;
if (NULL != UIGraphicsBeginImageContextWithOptions)
    UIGraphicsBeginImageContextWithOptions(imageSize,NO,0);

else
    UIGraphicsBeginImageContext(imageSize);

CGContextRef context = UIGraphicsGetCurrentContext();

// Iterate over every window from back to front
for (UIWindow *window in [[UIApplication sharedApplication] windows]) 
{
    if (![window respondsToSelector:@selector(screen)] || [window screen] == [UIScreen mainScreen])
    {
        // -renderInContext: renders in the coordinate space of the layer,// so we must first apply the layer's geometry to the graphics context
        CGContextSaveGState(context);
        // Center the context around the window's anchor point
        CGContextTranslateCTM(context,[window center].x,[window center].y);
        // Apply the window's transform about the anchor point
        CGContextConcatCTM(context,[window transform]);
        // Offset by the portion of the bounds left of and above the anchor point
        CGContextTranslateCTM(context,-[window bounds].size.width * [[window layer] anchorPoint].x,-[window bounds].size.height * [[window layer] anchorPoint].y);

        // Render the layer hierarchy to the current context
        [[window layer] renderInContext:context];

        // Restore the context
        CGContextRestoreGState(context);
    }
}

// Retrieve the screenshot image
CGRect contentRectToCrop = CGRectMake(0,70,740,740);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage],contentRectToCrop);
UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];
UIGraphicsEndImageContext();

UIImageWriteToSavedPhotosAlbum(croppedImage,nil,nil);