点击状态栏回滚到顶部

一.新建一个类（继承NSObject）

.h文件声明方法
<pre>

• (void)show;
• (void)hide;
  </pre>

.m文件实现方法
<pre>
static UIWindow *window_;

• (void)initialize
  {
  window_ = [[UIWindow alloc] init];
  window_.frame = CGRectMake(0, 0, UIWidth, 20);
  window_.windowLevel = UIWindowLevelAlert;
  [window_ addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(windowClick)]];
  }

• (void)show
  {
  window_.hidden = NO;
  }

• (void)hide
  {
  window_.hidden = YES;

}

/**

• 监听窗口点击
  */

• (void)windowClick
  {
  UIWindow *window = [UIApplication sharedApplication].keyWindow;
  [self searchScrollViewInView:window];

}

• (void)searchScrollViewInView:(UIView *)superview
  {
  for (UIScrollView *subview in superview.subviews) {
  // 如果是scrollview, 滚动最顶部
  if ([subview isKindOfClass:[UIScrollView class]] && subview.isShowingOnKeyWindow) {
  CGPoint offset = subview.contentOffset;
  offset.y = - subview.contentInset.top;
  [subview setContentOffset:offset animated:YES];
  }

    // 继续查找子控件
    [self searchScrollViewInView:subview];
  

  }
  }

</pre>

注意：isShowOnKeyWindow方法请参参我的另一篇文章（判断View是否显示在屏幕上）http://www.jianshu.com/p/a9ab004e0619