ios 点击textfield，使textfield高度随键盘高

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = QFMRGBColor(222, 222, 222);
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillChangeFrame:) name:UIKeyboardWillChangeFrameNotification object:nil];
}
- (void)keyboardWillChangeFrame:(NSNotification *)note{
    CGRect frame = [note.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
    CGFloat duration = [note.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    self.viewToBottm.constant = SCREEN_HEIGHT - frame.origin.y;
    [UIView animateWithDuration:duration animations:^{
        [self.view layoutIfNeeded];
    }]; // textfield为xib创建，self.viewToBottm.constant为textfield距离view底部的距离
}

- (void)dealloc{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

效果如图