presentModalViewController:Animated is deprecated in ios6

Use this line & check:

[self presentViewController:imagePicker animated:YES completion:nil];

[[Picker presentingViewController] dismissViewControllerAnimated:YES completion:nil];

Instead of

 [[Picker parentViewControl] dismissModalViewControllerAnimated:YES];

and

[self presentViewController:picker animated:YES completion:nil];

Instead of

[self presentModalViewController:picker animated:YES];

As Vishal mentioned

[self presentViewController:imagePicker animated:YES completion:nil];
[self dismissViewControllerAnimated:YES completion:nil];

make sure you have added "completion:nil" as well

if ([self respondsToSelector:@selector(presentViewController:animated:completion:)])
{
    [self presentViewController:objSignupViewController animated:^{} completion:nil];
}
else
{
    [self presentModalViewController:objSignupViewController animated:YES];
}

Use:

[self presentViewController:imagePicker animated:YES completion:nil];

And then for your dismissal modal use:

[self dismissViewControllerAnimated:controller completion:nil];

or

[self dismissViewControllerAnimated:YES completion:nil];