UITextfield 自定义键盘 mark!

UITextfield获取焦点时，进入textFieldShouldBeginEditing方法，在这个方法中注册两个通知：

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

//隐藏键盘

- (void)keyboardWillShow:(NSNotification *)Notification{

    UIWindow* tempWindow = [[[UIApplication sharedApplication] windows] objectAtIndex:1];
    [tempWindow setAlpha:0];
}

//显示自定义键盘- (void)keyboardWasShown:(NSNotification *) Notification{

// 显示自定义键盘 

}