監(jiān)聽(tīng)鍵盤(pán)變化的通知。有改變的，顯示的，隱藏的幾個(gè)系統(tǒng)通知。

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillChange:) name:UIKeyboardWillChangeFrameNotification  object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillChangeFrameNotification  object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];

這么處理，感覺(jué)跟隨鍵盤(pán)一起走比較自然一些。顯示和隱藏的通知記錄狀態(tài)，改變的通知去改變尺寸做動(dòng)畫(huà)，（暫時(shí)這么處理的，可能有更好的解決方案，還沒(méi)發(fā)現(xiàn)）

#pragma mark *************** 鍵盤(pán)通知 ***************
-(void)keyboardWillChange:(NSNotification *)note {

    NSDictionary *userInfo = note.userInfo;
    CGRect keyboardFrame =[userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
    CGFloat keyboardY = keyboardFrame.origin.y;
    CGFloat duration = [userInfo[UIKeyboardAnimationDurationUserInfoKey] floatValue];
    
    if (duration == 0) {//切換輸入法
        self.containerView.mj_y = keyboardY - SCREENHEIGHT;
    }else{
        
        [UIView animateWithDuration:duration delay:0.0 options:7 << 16 animations:^{
            self.containerView.mj_y = keyboardY - SCREENHEIGHT;
            if (self.keyboardView.alpha == 0) {
                [self.chatTableView mas_updateConstraints:^(MASConstraintMaker *make) {
                    make.bottom.equalTo(self.keyboardView.mas_top).offset(-5);
                }];
            }else{
                [self.chatTableView mas_updateConstraints:^(MASConstraintMaker *make) {
                    make.bottom.equalTo(self.keyboardView.mas_top).offset(-BottomH-5+50);
                }];
            }
            [self.containerView layoutIfNeeded];
        } completion:nil];
    }
}

-(void)keyboardWillShow:(NSNotification *)note {
    self.keyboardView.alpha = 1;
}

- (void)keyboardWillHide:(NSNotification *)note {
    self.keyboardView.alpha = 0;
}