iOS开发之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

#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
    double duration = [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<span style="background-color: rgb(240, 240, 240);">self.toolbar就是我的输入框。</span>

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

.h文件中声明

@interface UIView (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

@implementation UIView (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
{
    return self.frame.origin.x;
}

- (CGFloat)y
{
    return self.frame.origin.y;
}

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

- (CGFloat)centerX
{
    return self.center.x;
}

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

- (CGFloat)centerY
{
    return self.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
{
    return self.frame.size.height;
}

- (CGFloat)width
{
    return self.frame.size.width;
}

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

- (CGSize)size
{
    return self.frame.size;
}

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

- (CGPoint)origin
{
    return self.frame.origin;
}
@end