问题
I want to do something similar to UIAlertView, ie - without reference to any UIView or UIViewController, present a UIViewController on top of all windows using presentModalViewController.
Looking at the documentation I can't find a way in which this is possible!
In OS4, there is something like this:
UIWindow *window = [UIApplication sharedApplication].keyWindow
UIViewController *rootViewController = window.rootViewController
...but this is not possible in OS3.
Does anyone know how to achieve the same effect in OS3?
Thanks!
OK - so I solved this with a myriad of delegate callbacks to the ViewController itself! Although it's the proper way to achieve this, it did seem kind-of odd that's it's not possible at any stage in execution get a handle to the top View Controller for alerts (etc).
If anyone knows how to achieve this, I'd be still really interested!
回答1:
UIAlertView creates its own UIWindow above your application's main window, makeKeyAndVisible-s it, and animates in its own views in that window.
来源：https://stackoverflow.com/questions/3725339/how-does-uialertview-show-work