iOS6 problems to Tweet in UITabBarController using image taken from UIImagePickerController - xcode

Question

After picking image from UIImagePickerController I want to Tweet it but there is error!
Warning: Attempt to present <SLTwitterComposeViewController: 0x210d84b0> on <UITabBarController: 0x1fd67650> while a presentation is in progress!
P.S
This is tabbar application (4 tabbars)
All code:
-(void)useCamera:(id)sender
{
if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]){
UIImagePickerController *imagePicker =[[UIImagePickerController alloc] init];
imagePicker.delegate = self;
imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
imagePicker.mediaTypes = #[(NSString *) kUTTypeImage];
imagePicker.allowsEditing = NO;
[self presentViewController:imagePicker animated:YES completion:nil];
_newMedia = YES;
}
}
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
NSString *mediaType = info[UIImagePickerControllerMediaType];
[self dismissViewControllerAnimated:YES completion:nil];
if ([mediaType isEqualToString:(NSString *)kUTTypeImage]) {
[self buttonTweet:info[UIImagePickerControllerOriginalImage]];
}
}
- (IBAction)buttonTweet:(id)sender {
SLComposeViewController *composeController = [SLComposeViewController composeViewControllerForServiceType:SLServiceTypeTwitter];
[composeController setInitialText:[NSString stringWithFormat:#"#this is tweet text"]];
[composeController addImage:sender];
[composeController addURL: [NSURL URLWithString:#"http://www.abc.com"]];
[self presentViewController:composeController animated:YES completion:nil];
}

Answer 1

You are presenting a new view controller while the old one is still disappearing. You can present the new one upon completion of the other animation by doing it like this:
[self dismissViewControllerAnimated:YES completion:^{
if ([mediaType isEqualToString:(NSString *)kUTTypeImage]) {
[self buttonTweet:info[UIImagePickerControllerOriginalImage]];
}
}];