键盘通知

 

  由于键盘的通知是系统自动的，因此可以不用创建通知，只需要注册一个监听器监听即可，当收到相应的通知去执行方法。    

键盘状态改变的时候,系统会发出一些特定的通知

    UIKeyboardWillShowNotification // 键盘即将显示

    UIKeyboardDidShowNotification // 键盘显示完毕

    UIKeyboardWillHideNotification // 键盘即将隐藏

    UIKeyboardDidHideNotification // 键盘隐藏完毕

    UIKeyboardWillChangeFrameNotification // 键盘的位置尺寸即将发生改变

    UIKeyboardDidChangeFrameNotification // 键盘的位置尺寸改变完毕

    

    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)

 

- (void)viewDidLoad {

        //监听键盘frame变化的通知，键盘位置发生变化时，让输入框位置也随之变化。

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

}

 

- (void)receiveKeyboardFrameChangeNotification:(NSNotification *)noti{

        NSLog(@"%@",noti.userInfo);

    /*

     {

     UIKeyboardAnimationCurveUserInfoKey = 7;

     UIKeyboardAnimationDurationUserInfoKey = "0.25";

     UIKeyboardBoundsUserInfoKey = "NSRect: {{0, 0}, {375, 216}}";

     UIKeyboardCenterBeginUserInfoKey = "NSPoint: {187.5, 775}";

     UIKeyboardCenterEndUserInfoKey = "NSPoint: {187.5, 775}";

     UIKeyboardFrameBeginUserInfoKey = "NSRect: {{0, 667}, {375, 216}}";

     UIKeyboardFrameEndUserInfoKey = "NSRect: {{0, 667}, {375, 216}}";

     UIKeyboardIsLocalUserInfoKey = 1;

     }

     */

    

        //NSValue值类,基本类型和结构体不能直接放入数组和字典中，如果需要把结构体放入数组或字典，那么必须把结构体转换为NSValue，然后把NSValue放入字典或数组。

    NSValue *value = [noti.userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];

    

        //CGRect rect = [value CGRectValue];

    CGRect rect;

    [value getValue:&rect];

    

    

    [UIView beginAnimations:nil context:nil];

    [UIView setAnimationDuration:[[noti.userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey] floatValue]];

        //7是键盘动画专用速率

    //[noti.userInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey] integerValue] = 7

    [UIView setAnimationCurve:[[noti.userInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey] integerValue]];

    _inputView.frame = CGRectMake(0, rect.origin.y-40, 375, 40);

    _table.frame = CGRectMake(0, 0, 375, _inputView.frame.origin.y);

    if (_array.count>1) {

        [_table scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:_array.count-1 inSection:0] atScrollPosition:UITableViewScrollPositionNone animated:NO];

    }

    

    [UIView commitAnimations];

    

    

}