问题
I have a UIViewController (parent) that calls presentModalViewController with another UIViewController (child) on viewDidLoad.
If parent doesn't have a UINavigationController, then presentModalViewController does nothing. If it has a UINavigationController, then presentModalViewController shows child as expected.
Is this the standard behavior of presentModalViewController or is there something else at play here?
回答1:
It is because you are presenting it in viewDidLoad, try presenting it in viewDidAppear.
回答2:
Debug your app and look if the child-view isn't nil, if it's nil then it's not standard behavior, otherwise I think it's a standard behavior..
Hope, it helps..
来源：https://stackoverflow.com/questions/4059790/presentmodalviewcontroller-does-nothing