iOS开发中的键盘高度变化处理

在ios开发中，键盘很常用。在sdk版本5.0以前，键盘高度是固定值216px；5.0出来以后，键盘高度会随着键盘语言变化（中文要高些），在这种情况下一般而言对于界面需要重新布局。方法是利用NSNotificationCenter。
UIKeyboardWillShowNotification;UIKeyboardDidShowNotification; UIKeyboardWillHideNotification; UIKeyboardDidHideNotification;
这几个notification是5.0sdk之前就有的，顾名思义就知道意思了。
UIKeyboardWillChangeFrameNotification __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_5_0);UIKeyboardDidChangeFrameNotification __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_5_0);
这两个是sdk 5.0以后出来的，用来处理键盘高度的变化。
使用方法是：首先在notification注册观察者，比如：
if([[[UIDevice currentDevice] systemVersion] floatValue] >= 5.0) { [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillChangeFrame:) name:UIKeyboardWillChangeFrameNotification object:nil];}
当键盘高度将要变化时，就会收到通知，在通知的参数中可以得到键盘目前的高度和变化的目标高度，比如：
-(void)keyboardWillChangeFrame:(NSNotification*)notif{#if __IPHONE_OS_VERSION_MIN_REQUIRED >= __IPHONE_3_2 NSValue *keyboardBoundsValue = [[notif userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey]; #else NSValue *keyboardBoundsValue = [[notif userInfo] objectForKey:UIKeyboardBoundsUserInfoKey]; #endif CGRect keyboardEndRect = [keyboardBoundsValue CGRectValue]; CGRect inputFrame = self.feedBackTextView.frame; //kb 216 vs textFrame 185 float delta = keyboardEndRect.size.height - 216; float originalHeight = inputFrame.size.height; inputFrame.size.height = 185 - delta; if (inputFrame.size.height != originalHeight) { self.feedBackTextView.frame = inputFrame; self.feedBackBackgroundView.frame = inputFrame; }}
另外一些从notification.userInfo中可以取得的key如下：
UIKeyboardFrameBeginUserInfoKey // NSValue of CGRectUIKeyboardFrameEndUserInfoKey // NSValue of CGRectUIKeyboardAnimationDurationUserInfoKey // NSNumber of doubleUIKeyboardAnimationCurveUserInfoKey // NSNumber of double
notif中userInfo的完整信息如下 ：
keyboardChange:{ UIKeyboardAnimationCurveUserInfoKey = 0; UIKeyboardAnimationDurationUserInfoKey = "0.25"; UIKeyboardBoundsUserInfoKey = "NSRect: {{0, 0}, {320, 216}}"; UIKeyboardCenterBeginUserInfoKey = "NSPoint: {160, 372}"; UIKeyboardCenterEndUserInfoKey = "NSPoint: {160, 588}"; UIKeyboardFrameBeginUserInfoKey = "NSRect: {{0, 264}, {320, 216}}"; UIKeyboardFrameChangedByUserInteraction = 0; UIKeyboardFrameEndUserInfoKey = "NSRect: {{0, 480}, {320, 216}}";}
下面是一个完整的解决方案，用户需要知道键盘高度的细致变化

下面这个解决方案就只考虑键盘出现和消失的处理