思路相同、寫法不一樣而已

OC

//添加檢測(cè)者
 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillChangeFrame:) name:UIKeyboardWillChangeFrameNotification object:nil];
//移除通知
- (void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}
// 監(jiān)聽
- (void)keyboardWillChangeFrame:(NSNotification *)note
{
    // 修改約束
    CGFloat keyboardY = [note.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue].origin.y;
    CGFloat screenH = [UIScreen mainScreen].bounds.size.height;

    //控件距離底部約束
    self.bottomMargin.constant = screenH - keyboardY;
    
    // 執(zhí)行動(dòng)畫
    CGFloat duration = [note.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    [UIView animateWithDuration:duration animations:^{
        [self.view layoutIfNeeded];
    }];
}

Swift2.3

     // 注冊(cè)通知監(jiān)聽鍵盤彈出和消失
     NSNotificationCenter.defaultCenter().addObserver(self , selector: "keyboardChange:", name: UIKeyboardWillChangeFrameNotification, object: nil)
     deinit
        {
            NSNotificationCenter.defaultCenter().removeObserver(self)
        }

   // 只要鍵盤改變就會(huì)調(diào)用
    func keyboardChange(notify: NSNotification)
    {
        print(notify)
        // 1.取出鍵盤最終的rect
        let value = notify.userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue
        let rect = value.CGRectValue()

        // 2.修改工具條的約束
        // 彈出 : Y = 409 height = 258
        // 關(guān)閉 : Y = 667 height = 258
        // 667 - 409 = 258
        // 667 - 667 = 0
        let height = UIScreen.mainScreen().bounds.height

        //更改約束
        toolbarBottonCons?.constant = -(height - rect.origin.y)
        
        // 3.更新界面
        let duration = notify.userInfo![UIKeyboardAnimationDurationUserInfoKey] as! NSNumber
        
        UIView.animateWithDuration(duration.doubleValue) { () -> Void in
            self.view.layoutIfNeeded()
        }
    }

Swift3.0

// 0.注冊(cè)通知監(jiān)聽鍵盤彈出和消失
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardChange(notify:)), name: NSNotification.Name.UIKeyboardWillChangeFrame, object: nil)
deinit {
        NotificationCenter.default.removeObserver(self)
    }
/// 只要鍵盤改變就會(huì)調(diào)用
    func keyboardChange(notify:NSNotification)
    {
        print(notify)
         // 1.取出鍵盤最終的rect
        let value = notify.userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue
        let rect = value.cgRectValue
        
        // 2.修改工具條的約束
        // 彈出 : Y = 409 height = 258
        // 關(guān)閉 : Y = 667 height = 258
        // 667 - 409 = 258
        // 667 - 667 = 0
        let height = UIScreen.main.bounds.height
        
        toolbar.snp.updateConstraints { (make) in
            make.bottom.equalTo(-(height - rect.origin.y))
        }
        
        // 3.更新界面
        let duration = notify.userInfo![UIKeyboardAnimationDurationUserInfoKey] as! NSNumber
        UIView.animate(withDuration: TimeInterval(duration)) { 
            self.view.layoutIfNeeded()
        }
        
    }