IOS 监听键盘的通知（NSNotificationCenter）

通知方法：

/**
 *  当键盘改变了frame(位置和尺寸)的时候调用
 */
- (void)keyboardWillChangeFrame:(NSNotification *)note
{
    // 设置窗口的颜色
    self.view.window.backgroundColor = self.tableView.backgroundColor;
    
    // 0.取出键盘动画的时间
    CGFloat duration = [note.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    
    // 1.取得键盘最后的frame
    CGRect keyboardFrame = [note.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
    
    // 2.计算控制器的view需要平移的距离
    CGFloat transformY = keyboardFrame.origin.y - self.view.frame.size.height;
    
    // 3.执行动画
    [UIView animateWithDuration:duration animations:^{
        self.view.transform = CGAffineTransformMakeTranslation(0, transformY);
    }];
}

/*
 UIKeyboardAnimationCurveUserInfoKey = 7;  // 动画的执行节奏(速度)
 UIKeyboardAnimationDurationUserInfoKey = "0.25"; // 键盘弹出隐藏动画所需要的时间
 UIKeyboardBoundsUserInfoKey = "NSRect: {{0, 0}, {320, 216}}";
 UIKeyboardCenterBeginUserInfoKey = "NSPoint: {160, 588}";
 UIKeyboardCenterEndUserInfoKey = "NSPoint: {160, 372}";
 UIKeyboardFrameChangedByUserInteraction = 0;
 
 // 键盘弹出
 UIKeyboardFrameBeginUserInfoKey = "NSRect: {{0, 480}, {320, 216}}";// 键盘刚出来那一刻的frame
 UIKeyboardFrameEndUserInfoKey = "NSRect: {{0, 264}, {320, 216}}"; //  键盘显示完毕后的frame
 
 // 键盘隐藏
 UIKeyboardFrameBeginUserInfoKey = "NSRect: {{0, 264}, {320, 216}}";
 UIKeyboardFrameEndUserInfoKey = "NSRect: {{0, 480}, {320, 216}}";
 */

调用通知：

    // 2.监听键盘的通知
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillChangeFrame:) name:UIKeyboardWillChangeFrameNotification object:nil];

移出监听 ARC的情况

-(void)dealloc
{

    //[super dealloc]; 非ARC的情况需要这一步
    [[NSNotificationCenter defaultCenter]removeObserver:self];
}