An error occurred while using presentModalViewController.

Function Description:
The existing UI structure is VC0, VC1, and VC2. VC0 is the rootViewController of the application and contains the view of VC1. VC1 also contains the view of VC2. There is a button in VC2. Click it and call the system's mail function to bring up the mail sending interface.
 
Problem:
Use VC2 as the delegate of MFMailComposeViewController. click the button and perform the following operations:
[Self presentModalViewController: mailPicker animated: YES];
[MailPicker release];
 
It is used to display the email interface, but the problem occurs and is normal on the ipad. If it is replaced with an iPhone, it cannot be displayed normally, the device cannot be identified horizontally, or the layout of other controls in VC2 is affected.
 
Whether it is viewing the scaling support of controls and interfaces or supporting direction conversion, it still cannot be solved. In addition, if the interface is displayed in VC2, the interface may be blocked by other interfaces or controls in VC0 or VC1 due to the hierarchical relationship.
 
Solution:
Similar interface display is implemented in the VC at the root layer. It turns out that it is no problem to implement this function in VC0.

From zhao_yin notepad