iOS监听键盘高度的变化

最近做的项目中，有一个类似微博中的评论转发功能，屏幕底端有一个输入框用textView来做，当textView成为第一响应者的时候它的Y值随着键盘高度的改变而改变，保证textView紧贴着键盘，但又不会被键盘挡住。

下面是我实现的方法：（利用通知）

// 键盘通知
// 键盘的frame发生改变时发出的通知（位置和尺寸）
// UIKeyboardWillChangeFrameNotification
// UIKeyboardDidChangeFrameNotification
// 键盘显示时发出的通知
// UIKeyboardWillShowNotification
// UIKeyboardDidShowNotification
// 键盘隐藏时发出的通知
// UIKeyboardWillHideNotification
// UIKeyboardDidHideNotification

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillChangeFrame:) name:UIKeyboardWillChangeFrameNotification object:nil];//在这里注册通知

下面是监听通知：

pragma mark - 监听方法

/**

• 键盘的frame发生改变时调用（显示、隐藏等）
  */

• (void)keyboardWillChangeFrame:(NSNotification *)notification
  {
  // if (self.picking) return;
  /**
  notification.userInfo = @{
  // 键盘弹出隐藏后的frame
  UIKeyboardFrameEndUserInfoKey = NSRect: {{0, 352}, {320, 216}},
  // 键盘弹出隐藏所耗费的时间
  UIKeyboardAnimationDurationUserInfoKey = 0.25,
  // 键盘弹出隐藏动画的执行节奏（先快后慢，匀速）
  UIKeyboardAnimationCurveUserInfoKey = 7
  }
  */

  NSDictionary *userInfo = notification.userInfo;

  // 动画的持续时间
  doubleduration = [userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];

  // 键盘的frame
  CGRect keyboardF = [userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];

  // 执行动画
  [UIView animateWithDuration:duration animations:^{
  // 工具条的Y值 == 键盘的Y值 - 工具条的高度
  if(keyboardF.origin.y > self.view.height) { // 键盘的Y值已经远远超过了控制器view的高度
  self.toolbar.y = self.view.height - self.toolbar.height;//这里的self.toolbar就是我的输入框。

  }else{
      self.toolbar.y = keyboardF.origin.y - self.toolbar.height;
  }

  }];
  }

当然，这里我为UIView写了一个类别，实现如下：
.h文件中声明

@interfaceUIView (Extension)
@property(nonatomic, assign) CGFloat x;
@property(nonatomic, assign) CGFloat y;
@property(nonatomic, assign) CGFloat width;
@property(nonatomic, assign) CGFloat height;
@property(nonatomic, assign) CGFloat centerX;
@property(nonatomic, assign) CGFloat centerY;
@property(nonatomic, assign) CGSize size;
@property(nonatomic, assign) CGPoint origin;
@end
.m文件中实现（重写setter 和 getter）

@implementationUIView (Extension)

• (void)setX:(CGFloat)x
  {
  CGRect frame = self.frame;
  frame.origin.x = x;
  self.frame = frame;
  }

• (void)setY:(CGFloat)y
  {
  CGRect frame = self.frame;
  frame.origin.y = y;
  self.frame = frame;
  }

• (CGFloat)x
  {
  returnself.frame.origin.x;
  }

• (CGFloat)y
  {
  returnself.frame.origin.y;
  }

• (void)setCenterX:(CGFloat)centerX
  {
  CGPoint center = self.center;
  center.x = centerX;
  self.center = center;
  }

• (CGFloat)centerX
  {
  returnself.center.x;
  }

• (void)setCenterY:(CGFloat)centerY
  {
  CGPoint center = self.center;
  center.y = centerY;
  self.center = center;
  }

• (CGFloat)centerY
  {
  returnself.center.y;
  }

• (void)setWidth:(CGFloat)width
  {
  CGRect frame = self.frame;
  frame.size.width = width;
  self.frame = frame;
  }

• (void)setHeight:(CGFloat)height
  {
  CGRect frame = self.frame;
  frame.size.height = height;
  self.frame = frame;
  }

• (CGFloat)height
  {
  returnself.frame.size.height;
  }

• (CGFloat)width
  {
  returnself.frame.size.width;
  }

• (void)setSize:(CGSize)size
  {
  CGRect frame = self.frame;
  frame.size = size;
  self.frame = frame;
  }

• (CGSize)size
  {
  returnself.frame.size;
  }

• (void)setOrigin:(CGPoint)origin
  {
  CGRect frame = self.frame;
  frame.origin = origin;
  self.frame = frame;
  }

• (CGPoint)origin
  {
  returnself.frame.origin;
  }
  @end
  有需要的朋友可以直接用