iOS---scrollview自动下移问题

- (void)loadScrollView

{

    // 禁止自动调整scrollview的内边距，防止scrollview下移64px

    self.automaticallyAdjustsScrollViewInsets = NO;

    self.mainScrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 120, SCREEN_WIDTH, SCREEN_HEIGHT-130)];

    self.mainScrollView.backgroundColor = [UIColor whiteColor];

    self.mainScrollView.delegate = self;

    self.mainScrollView.pagingEnabled = YES;

    self.mainScrollView.showsVerticalScrollIndicator = NO;

    self.mainScrollView.showsHorizontalScrollIndicator = NO;

    [self.view addSubview: self.mainScrollView];

    self.mainScrollView.contentSize = CGSizeMake(SCREEN_WIDTH*self.titleArray.count, 0);

}