in iOS 7 there is no problem for this method:
_rootViewController.modalPresentationStyle = UIModalPresentationCurrentContext;
[_rootViewController presentViewController:self animated:NO completion:nil];
But in iOS 8 it did nothing.How to solve it? Is it a Bug for iOS 8?
Finally made it work in iOS 8 after reading the UIPresentationController help and this post
You can make the modal view controller inherit from UIViewControllerTransitioningDelegate
and override presentationControllerForPresentedViewController:...
returning an instance of TransparentPresentationController which inherits from UIPresentationController
and overrides shouldRemovePresentersView
My answer is more simple, below code. This works in iOS8 (XCode6 GM seed).