This is work around to get rid of mentioned situation.
I assume you are using becomeFirstResponder
for textField. Write below code in class which is presented modally.
-(void)viewDidAppear:(BOOL)animated{
[self performSelector:@selector(txtFieldResponder) withObject:nil afterDelay:0.1];
}
-(void)txtFieldResponder{
[self.txt becomeFirstResponder];
}
Hope this helps.