iOS开发（5）动态监听键盘通知
众所周知，在ios开发的页面传值和监听代理两个环节中，通知Notification是一个重量级角色。
这里主要介绍一下一种特殊ios自带的通知，如
UIKeyboardWillChangeFrameNotification
首先，让我们创建一个监听键盘的通知
//注册观察者
[[NSNotificationCenterdefaultCenter]addObserver:selfselector:@selector(keyBoardWasChange:)name:UIKeyboardWillChangeFrameNotificationobject:nil];
这种通知是被苹果封装在UIWindow的.h文件中
UIKIT_EXTERNNSString *const UIKeyboardWillShowNotification;
UIKIT_EXTERNNSString *const UIKeyboardDidShowNotification;
UIKIT_EXTERNNSString *const UIKeyboardWillHideNotification;
UIKIT_EXTERNNSString *const UIKeyboardDidHideNotification;
UIKIT_EXTERNNSString *const UIKeyboardFrameBeginUserInfoKey NS_AVAILABLE_IOS(3_2);// NSValue of CGRect
UIKIT_EXTERNNSString *const UIKeyboardFrameEndUserInfoKey NS_AVAILABLE_IOS(3_2);// NSValue of CGRect
UIKIT_EXTERNNSString *const UIKeyboardAnimationDurationUserInfoKeyNS_AVAILABLE_IOS(3_0);// NSNumber of double
UIKIT_EXTERNNSString *const UIKeyboardAnimationCurveUserInfoKey NS_AVAILABLE_IOS(3_0);// NSNumber of NSUInteger
以上就是关于键盘所有的通知类型,但是基本只需要UIKeyboardWillChangeFrameNotification这一个就可以做到你想要的做的。
下面来实现注册通知时的相应方法
- (void)keyBoardWasChange:(NSNotification *)noti
{
NSDictionary *infoDic = [noti userInfo];
//由字典的键值对可知键盘的位置属性
CGRect rect = [[infoDicobjectForKey:UIKeyboardFrameEndUserInfoKey]CGRectValue];
CGFloat f = self.textfieldView.frame.origin.y + self.textfieldView.frame.size.height;
CGFloat p = rect.origin.y;
//弹出键盘
if(p == 264)
{
//下面是我自己封装的动画，就是怕键盘遮住了输入框而将输入框上移的动作
[ZxkAnimationmoveAnimationWithView:self.textfieldViewfromPoint:CGPointMake(self.textfieldView.center.x,self.textfieldView.center.y)ToPoint:CGPointMake(self.textfieldView.center.x,self.textfieldView.center.y - f + 230)Duration:0.2];
}
//收回键盘
else if(p ==480)
{
[ZxkAnimationmoveAnimationWithView:self.textfieldViewfromPoint:CGPointMake(self.textfieldView.center.x,self.textfieldView.center.y - f + 230)ToPoint:CGPointMake(self.textfieldView.center.x,self.textfieldView.center.y)Duration:0.2];
}
//弹出中文选择框
else if(p ==228)
{
//没记错的话，中文框应该是36高
[ZxkAnimationmoveAnimationWithView:self.textfieldViewfromPoint:CGPointMake(self.textfieldView.center.x,self.textfieldView.center.y - f + 230)ToPoint:CGPointMake(self.textfieldView.center.x,self.textfieldView.center.y - f + 194)Duration:0.2];
}
}
输出通知的infoDic可以看到下面几个键值对
UIKeyboardAnimationCurveUserInfoKey = 0;
UIKeyboardAnimationDurationUserInfoKey = "0.25";
UIKeyboardBoundsUserInfoKey = "NSRect: {{0, 0}, {320, 216}}";
UIKeyboardCenterBeginUserInfoKey = "NSPoint: {160, 676}";
UIKeyboardCenterEndUserInfoKey = "NSPoint: {160, 460}";
UIKeyboardFrameBeginUserInfoKey = "NSRect: {{0, 568}, {320, 216}}";
UIKeyboardFrameChangedByUserInteraction = 0;
UIKeyboardFrameEndUserInfoKey = "NSRect: {{0, 352}, {320, 216}}";
我刚才获取的就是UIKeyboardFrameEndUserInfoKey这个里面的值，是一个NSRect类型，主要是键盘的当前frame
最后，大家千万不要忘记在dealloc方法中移除通知
- (void)dealloc
{
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillChangeFrameNotification object:nil];
//由于我用的是ARC,所以不需要[super dealloc]
}