键盘挡住UITextField 时上推View

- (void)textFieldDidBeginEditing:(UITextField *)textField
{
    [UIView beginAnimations:@"showKeyboardAnimation" context:nil];
    [UIView setAnimationDuration:0.30];
    self.view.frame = CGRectMake(self.view.frame.origin.x, self.view.frame.origin.y- 80, self.view.frame.size.width, self.view.frame.size.height);
    [UIView commitAnimations];
}