IOS UIScrollView 翻页，并且露出左边视图和右边视

- (void)loadView {  
    [super loadView];  
    self.title = @"主界面";  
    self.view.backgroundColor = [UIColor grayColor];  
      
    UIView * scrollBg = [[[UIView alloc] initWithFrame:CGRectMake(20, 10, 290, 400)] autorelease];  
    scrollBg.backgroundColor = [UIColor redColor];  
    scrollBg.clipsToBounds = YES;   //此句话重要，裁剪到边缘  
    [self.view addSubview:scrollBg];  
  
    UIScrollView * _activityPlaceScl = [[[UIScrollView alloc]initWithFrame:CGRectMake(25, 10, 240, 320)] autorelease];  
    _activityPlaceScl.pagingEnabled = YES;  
    _activityPlaceScl.backgroundColor = [UIColor clearColor];  
    _activityPlaceScl.clipsToBounds = NO;      //此句话重要，不裁剪到边缘  
    _activityPlaceScl.contentSize = CGSizeMake(_activityPlaceScl.frame.size.width * 5, _activityPlaceScl.frame.size.height);  
    _activityPlaceScl.showsHorizontalScrollIndicator = NO;  
    _activityPlaceScl.showsVerticalScrollIndicator = NO;  
    [scrollBg addSubview:_activityPlaceScl];  
      
    for (int page = 0; page < 5; page++) {  
        CGRect frame = _activityPlaceScl.frame;  
        UIButton *backgroundButton =  [UIButton buttonWithType:UIButtonTypeRoundedRect];  
        backgroundButton.frame = CGRectMake(frame.size.width * page + 10, 0, 220, 258);  
        [_activityPlaceScl addSubview:backgroundButton];  
    }  
}