键盘出现时“无法识别的选择器发送到实例”

Question

当我单击文本字段到我的应用程序屏幕并且键盘显示时，xcode调试器显示此错误：

[mainViewController keyboardWasShown]: unrecognized selector sent to instance 0x5867ac0

在mainViewController的viewDidLoad方法中，我正在调用registerForKeyboardNotifications方法：

[self registerForKeyboardNotifications];

这是它的实现（在mainViewController.m中）：

- (void)registerForKeyboardNotifications
{
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWasShown:) name:UIKeyboardDidShowNotification object:nil];
   [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillBeHidden:) name:UIKeyboardWillHideNotification object:nil];
}

// Called when the UIKeyboardDidShowNotification is sent.
- (void)keyboardWasShown:(NSNotification*)aNotification
{

}

// Called when the UIKeyboardWillHideNotification is sent
- (void)keyboardWillBeHidden:(NSNotification*)aNotification
{

}

知道可能出现什么问题吗？

Answer 1

确保通知选择器的末尾有冒号;这很重要，keyboardWasShown和keyboardWasShown:是不同的选择器。