监听键盘弹出，拿到键盘的高度

在viewDidLoad里注册通知，监听键盘变化

- (void)viewDidLoad

{

[super viewDidLoad];

//增加监听，当键盘出现或改变时收出消息

[[NSNotificationCenter defaultCenter] addObserver:self

selector:@selector(keyboardWillShow:)

name:UIKeyboardWillShowNotification

object:nil];

//增加监听，当键退出时收出消息

[[NSNotificationCenter defaultCenter] addObserver:self

selector:@selector(keyboardWillHide:)

name:UIKeyboardWillHideNotification

object:nil];

}

//当键盘出现或改变时调用

- (void)keyboardWillShow:(NSNotification *)aNotification

{

//获取键盘的高度

NSDictionary *userInfo = [aNotification userInfo];

NSValue *aValue = [userInfo objectForKey:UIKeyboardFrameEndUserInfoKey];

CGRect keyboardRect = [aValue CGRectValue];

int height = keyboardRect.size.height;

}

//当键退出时调用

- (void)keyboardWillHide:(NSNotification *)aNotification

{

}