title: UIScrollView does not scroll
body: <p>I got a problem about UIScrollView. I am making a custom view which inherits UIView. The view has a UIScrollView on which there are lots of buttons which should scroll left and right. The UIScrollView and buttons can show normally. But I cannot scroll the buttons. Could someone give me some suggestions? Thanks a lot!</p>
  
  <p>MZMPhotoCalenderSwitcher.h</p>
  
  <pre><code>#import &lt;UIKit/UIKit.h&gt;
  
  @interface MZMPhotoCalenderSwitcher : UIView &lt;UIScrollViewDelegate&gt;
  
  @property (strong, nonatomic) UIScrollView *topSwitcher;
  
  @end
  </code></pre>
  
  <p>MZMPhotoCalenderSwitcher.m</p>
  
  <pre><code>- (void)viewDidLoad
  {
      [super viewDidLoad];
      // Do any additional setup after loading the view.
      self.topSwitcher = [[UIScrollView alloc] initWithFrame:CGRectMake(0, LABEL_HEIGHT + VIEW_Y, self.view.bounds.size.width, TOP_SWITCHER_HEIGHT)];
      self.topSwitcher.backgroundColor = [UIColor greenColor];
      self.topSwitcher.pagingEnabled = YES;
      self.topSwitcher.showsHorizontalScrollIndicator = NO;
      self.topSwitcher.showsVerticalScrollIndicator = NO;
  
      [self add:3 ButtonsOnView:self.topSwitcher withButtonWidth:44.8f andHeight:20.0f];
  }
  
  - (void)add:(int)num ButtonsOnView:(UIScrollView *)view withButtonWidth:(CGFloat)width andHeight:(CGFloat)height
  {
      CGFloat totalTopSwitcherWidth = num * width;
      [view setContentSize:CGSizeMake(totalTopSwitcherWidth, view.bounds.size.height)];
      CGFloat xOffset = 0.0f;
  
      for (int i=1; i&lt;=num; i++)
      {
          UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
          [button setFrame:CGRectMake(xOffset, 0, width, height)];
          xOffset += width;
          [button setTitle:[NSString stringWithFormat:@"%d", i] forState:UIControlStateNormal];
  
          button.titleLabel.font = [UIFont systemFontOfSize:10];
          [button setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
          [button setTitleColor:[UIColor blackColor] forState:UIControlStateSelected];
          [button setTag:i];
          [button addTarget:self action:@selector(buttonEvent) forControlEvents:UIControlEventTouchUpInside];
  
          if (i % 2 == 0)
              [button setBackgroundColor:[UIColor yellowColor]];
          else
              [button setBackgroundColor:[UIColor redColor]];
  
          [view addSubview:button];
      }
  }
  </code></pre>