Assertion failure in -[ISHPullUpViewController addViewOfSubViewController:belowView:], ISHPullUpViewController.m:625

[1371030]

ISHPullUpViewController *isv = [[ISHPullUpViewController alloc] init];
isv.contentViewController = vc;

Assertion failure in -[ISHPullUpViewController addViewOfSubViewController:belowView:], ISHPullUpViewController.m:625
Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'addViewOfSubViewController: should not be called for view controllers already have a parent view controller'