Question

How to create LoginScreen in UIViewController ?
It should appear like UIAlertView after tapping a button.

Answer 1

Since iOS 5, you can add a text field or a pair of text fields to a UIAlertView by modifying its alertViewStyle property.

There are four different options for alertViewStyle:

 UIAlertViewStyleDefault = 0,          // No text fields
 UIAlertViewStyleSecureTextInput,      // A single text field with secure input
 UIAlertViewStylePlainTextInput,       // A single text field with plaintext input
 UIAlertViewStyleLoginAndPasswordInput // A pair of text fields, one with plaintext and one with a password

To access the text fields, you call textFieldAtIndex: on the UIAlertView instance. According to the documentation, the indices begin with 0.

Legacy answer, before iOS 5.0:

If you are looking to present a UIAlertView with a textbox, this is not supported in iOS in any public API, although you could walk the view hierarchy and add your own textbox.

Alternatively, create a new UIViewController subclass and present it modally. Then, you can check the values when the view is dismissed.