UI键盘处理

1.键盘的监听

• 一般来说，键盘的监听用通知来实现（NSNotificationCenter）

方法一

• 同时监听键盘的显示和隐藏

//监听键盘的显示
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(showKeyBoard:) name:UIKeyboardWillShowNotification object:nil];

//监听键盘的隐藏
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(hideKeyBoard:) name:UIKeyboardWillHideNotification object:nil];

• 实现方法

- (void)showKeyBoard:(NSNotification * )note
{
    NSLog(@"%@",note.userInfo);

    //界面的底部约束，[note.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue].size.height 键盘最终的frame(动画执行完毕后)
    self.chatButtonCon.constant = [note.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue].size.height;


    //键盘弹出的时间
    CGFloat duration = [note.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];

    //键盘弹出动画
    [UIView animateWithDuration:duration animations:^{
        [self.view layoutIfNeeded];
    }];
}

- (void)hideKeyBoard:(NSNotification * )note
{

    //界面的底部约束
    self.chatButtonCon.constant = 0;

    //键盘弹出的时间
    CGFloat duration = [note.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];

    //键盘弹出动画
    [UIView animateWithDuration:duration animations:^{
        [self.view layoutIfNeeded];
    }];

}

方法二

• 注册监听器

  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(changeKeyBoard:) name:UIKeyboardWillChangeFrameNotification object:nil];
  

• 注意是取出 UIKeyboardAnimationDurationUserInfoKey的origin的Y值

- (void)changeKeyBoard:(NSNotification * )note
{
    CGFloat height = [UIScreen mainScreen].bounds.size.height - [note.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue].origin.y;

    CGFloat duration = [note.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];

    self.view.transform = CGAffineTransformMakeTranslation(0, -height);

    [UIView animateWithDuration:duration animations:^{

        [self.view layoutIfNeeded];
    }];
}

取消键盘（textfiled）(3个方法)

1、[self.textfiled resignFirstResponder]
2、[self.textfiled endEditing:YES]
2、[self.view endEditing:YES]

注意

• 键盘显示的时候 [note.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue].size.height 的值为图红的高度

</br>

• 键盘隐藏的时候 [note.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue].size.height 的值为图红的高度

通知传递下来的 (NSNotification * )note 对象的 userInfo

note.userInfo

    UIKeyboardAnimationCurveUserInfoKey = 7;
    UIKeyboardAnimationDurationUserInfoKey = "0.25";
    UIKeyboardBoundsUserInfoKey = "NSRect: {{0, 0}, {414, 271}}";
    UIKeyboardCenterBeginUserInfoKey = "NSPoint: {207, 871.5}";
    UIKeyboardCenterEndUserInfoKey = "NSPoint: {207, 600.5}";
    UIKeyboardFrameBeginUserInfoKey = "NSRect: {{0, 736}, {414, 271}}";
    UIKeyboardFrameEndUserInfoKey = "NSRect: {{0, 465}, {414, 271}}";
    UIKeyboardIsLocalUserInfoKey = 1;</br>

系统发出键盘通知时,会附带一下跟键盘有关的额外信息(字典),字典常见的key如下:
UIKeyboardFrameBeginUserInfoKey // 键盘刚开始的frame
UIKeyboardFrameEndUserInfoKey // 键盘最终的frame(动画执行完毕后)
UIKeyboardAnimationDurationUserInfoKey // 键盘动画的时间
UIKeyboardAnimationCurveUserInfoKey // 键盘动画的执行节奏(快慢)