Objective c 键盘更改时（如从NumberPad更改为默认值）是否会发送任何通知

我正试图弄清楚，当键盘发生变化时，我如何得到通知。我想做的是在4和5型键盘（NumberPad和PhonePad）上添加一个“完成”按钮，一切正常，除了当我使用默认KB类型从文本字段转换时，键盘显示未被触发的通知

以下是我得到的：

- (void)viewDidLoad
{
    [super viewDidLoad];

    [[NSNotificationCenter defaultCenter] addObserver:self 
                                             selector:@selector(keyboardDidShow:) 
                                                 name:UIKeyboardDidShowNotification 
                                               object:nil]; 

}

然后，我为当前KB类型和正在编辑的当前文本字段添加了一个属性：

#pragma mark - Delegate Methods
-(BOOL)textFieldShouldBeginEditing:(UITextField *)textField {
    self.currentKBType = textField.keyboardType;
    self.curTextField = textField;
    return YES;
}

然后，我根据当前KB类型决定是否添加“完成”按钮：

- (void)keyboardDidShow:(NSNotification *)note {
    if (self.currentKBType == 4 || self.currentKBType == 5) {
        [self addButtonToKeyboard];
    }
}

问题是，当键盘显示时会触发通知，但当键盘更改（从一个文本字段转换到另一个指定不同KB类型的文本字段）时不会触发通知

---

有什么建议吗？我遗漏了什么吗？

找到了答案。虽然有一点逻辑性，但效果完美。以下是我所做的： 为以下对象添加了私有属性：

@property (nonatomic) UIKeyboardType currentKBType;
@property(nonatomic,strong) UITextField *curTextField;
@property(nonatomic,strong) UIButton *doneButton;
@property(nonatomic) BOOL doneButtonDisplayed;

然后在两个TextField委托方法中添加以下逻辑：

-(BOOL)textFieldShouldBeginEditing:(UITextField *)textField {
    self.currentKBType = textField.keyboardType;
    if (textField.keyboardType == 4 || textField.keyboardType == 5) {
        if (!doneButtonDisplayed) {
            [self addButtonToKeyboard];
        }
    } else {
        if (doneButtonDisplayed) {
            [self removeButtonFromKeyboard];
        }
    }

    self.curTextField = textField;
    return YES;
}

在我在viewDidLoad中为VC注册的KeyboardDidShow通知中：

- (void)keyboardDidShow:(NSNotification *)note {
    if (self.currentKBType == 4 || self.currentKBType == 5) {
        if (!doneButtonDisplayed) {
            [self addButtonToKeyboard];
        }
    } else {
        if (doneButtonDisplayed) {
            [self removeButtonFromKeyboard];
        }
    }
}

以及这些方法中引用的两种方法：

- (void)addButtonToKeyboard {

    // create custom button
    doneButton = [UIButton buttonWithType:UIButtonTypeCustom];
    doneButton.frame = CGRectMake(0, 163, 106, 53);
    doneButton.adjustsImageWhenHighlighted = NO;

    [doneButton setImage:[UIImage imageNamed:@"DoneNormal.png"] forState:UIControlStateNormal];
    [doneButton setImage:[UIImage imageNamed:@"DoneHL.png"] forState:UIControlStateHighlighted];

    [doneButton addTarget:self action:@selector(resignKeyboard) forControlEvents:UIControlEventTouchUpInside];
    // locate keyboard view
    if ([[[UIApplication sharedApplication] windows] count] > 1) {
        UIWindow* tempWindow = [[[UIApplication sharedApplication] windows] objectAtIndex:1];
        UIView* keyboard;
        for(int i=0; i<[tempWindow.subviews count]; i++) {
            keyboard = [tempWindow.subviews objectAtIndex:i];
            // keyboard found, add the button
            if([[keyboard description] hasPrefix:@"<UIPeripheralHost"] == YES) {
                [keyboard addSubview:doneButton];
                self.doneButtonDisplayed = YES;
            }
        }

    }
}

- (void)removeButtonFromKeyboard {  
    [doneButton removeFromSuperview];
    self.doneButtonDisplayed = NO;
}

这将在显示NumberPad或PhonePad类型键盘时添加“完成”按钮，并将其从其他键盘类型中删除（仅当已添加时）

---

经过测试，效果很好。

代码运行正常。但当我第一次点击数字键盘时，就看不到“完成”按钮。您也可以这样做吗？

-(void)resignKeyboard {
    [self.curTextField resignFirstResponder];
    self.doneButtonDisplayed = NO;
}