iPhone UITextField mask

Is there built in support for input masks in UITextField? I could apply formatting after the text has been entered, but I'd like it to be there as the user is enter开发者_开发问答ing text.

If there is no build in support, how can tis be achieved?

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The iPhone doesn't support formatters like Cocoa does. You have to manage input filtering in the UITextFieldDelegate method:

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string

This method is called before any text appears in the field.