Print a temporarily saved image via AirPrint

Question

I've one question. Is it possible to print an image which is only temporarily saved? I saved the image as it is done in this example of a question on stackoverflow.

But when I try to use this picture for printing via AirPrint it doesn't work.

- (IBAction)btnPrintTapped:(id)sender {

    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) {
        [UIImagePNGRepresentation(image) writeToFile: @"/tmp/test.png" atomically: YES];
        UIImage *yourImage = [UIImage imageNamed:@"/tmp/test.png"];
        NSArray *itemsToShare = @[yourImage];
        UIActivityViewController *activityVC = [[UIActivityViewController alloc] initWithActivityItems:itemsToShare applicationActivities:nil];
        activityVC.excludedActivityTypes = @[ UIActivityTypeCopyToPasteboard, UIActivityTypeAssignToContact, UIActivityTypeSaveToCameraRoll, UIActivityTypeMail, UIActivityTypeMessage, UIActivityTypePostToFacebook, UIActivityTypePostToTwitter, UIActivityTypePostToWeibo]; 
        [self presentViewController:activityVC animated:YES completion:nil];
    }    
}

But the printer is able to print (I tested it with a fix image)...so the printer not seems to be the problem. Thanks for your help in advance.

UPDATE I did some changes to the code/added a few code lines:

[UIImagePNGRepresentation(image) writeToFile: @"/tmp/test.png" atomically: YES];

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString* path = [documentsDirectory stringByAppendingPathComponent:@"/tmp/test.png" ];
UIImage* image = [UIImage imageWithContentsOfFile:path];

UIImage *ImageItem = image;

But it only works when i set writeToFile: @"test.png"...but then I can only save an image once and not overwrite it.

When I do it with the code above there is one error:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: ' -[__NSPlaceholderArray initWithObjects:count:]: attempt to insert nil object from objects[0]'

Answer 1

After a bit trying it finally works now...

if (image != nil) {
        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
                                                             NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];
        NSString* path = [documentsDirectory stringByAppendingPathComponent:
                          @"test.png" ];
        NSData* data = UIImagePNGRepresentation(image);
        [data writeToFile:path atomically:YES];


        UIImage* image = [UIImage imageWithContentsOfFile:path];
        UIImage *yourImage = image;