UIPageContorollと拡大・ダブルタップに対応したスライドギャラリーを作る ref: http://qiita.com/tanshio/items/01cb5b25d3e9534ba07a

file0.m

- (void)setUpImages {

    self.itemScrollView.contentSize =  CGSizeMake(self.view.frame.size.width * 3, self.view.frame.size.width);

    self.itemScrollView.pagingEnabled = YES;
    self.itemScrollView.showsHorizontalScrollIndicator = NO;
    self.itemScrollView.showsVerticalScrollIndicator = NO;

    self.itemScrollView.delegate = self;

    self.itemControll.numberOfPages = 3;
    // 現在のページを0に初期化する。
    self.itemControll.currentPage = 0;


    for (int i = 0; i < 3 ; i++){

        UIImage *image = [UIImage imageNamed:@"dummy-item.jpg"];
        UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
        imageView.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.width);

        UIScrollView *innerScrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(self.view.frame.size.width * i, 0, self.view.frame.size.width, self.view.frame.size.width)];

        innerScrollView.delegate = self;

        innerScrollView.contentSize = imageView.bounds.size;

        imageView.tag = i + 1000;
        [innerScrollView addSubview:imageView];

        innerScrollView.minimumZoomScale = 1.0f;
        innerScrollView.maximumZoomScale = 5.0f;
        innerScrollView.showsHorizontalScrollIndicator = NO;
        innerScrollView.showsVerticalScrollIndicator = NO;
        innerScrollView.tag = i + 2000;

        UITapGestureRecognizer *doubleTapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(doubleTap:)];

        // ダブルタップを認識する設定にする
        doubleTapGesture.numberOfTapsRequired = 2;

        [innerScrollView addGestureRecognizer:doubleTapGesture];

        [self.itemScrollView addSubview:innerScrollView];
    }

}

- (void)doubleTap:(UIGestureRecognizer *)gesture {
    NSLog(@"%lu",gesture.view.tag);

    UIScrollView *tapScrollView = (UIScrollView*)[self.view viewWithTag:gesture.view.tag];

    if(tapScrollView.zoomScale == 1.0f)
    {
        // 現在の5倍の倍率にする
        float newScale = tapScrollView.zoomScale * 5;

        //拡大する領域を求める
        CGRect zoomRect = [self zoomRectForScale:newScale withCenter:[gesture locationInView:gesture.view] view:gesture.view];

        // タップした位置を拡大する
        [tapScrollView zoomToRect:zoomRect animated:YES];
    } else {
        // 倍率1に戻す
        [tapScrollView setZoomScale:1.0 animated:YES];
    }
}

// 指定の座標を中心にして拡大する領域を求める
- (CGRect)zoomRectForScale:(float)scale withCenter:(CGPoint)center view:(UIView*)view {
    CGRect zoomRect;

    // 倍率から拡大する縦横サイズを求める
    zoomRect.size.height = [view frame].size.height / scale;
    zoomRect.size.width  = [view frame].size.width / scale;

    // 座標(左上)を設定する
    zoomRect.origin.x = center.x - (zoomRect.size.width/2.0);
    zoomRect.origin.y = center.y - (zoomRect.size.height/2.0);

    // 領域を返す
    return zoomRect;
}

- (IBAction)onValueChange:(id)sender {

    // スクロールビューのframeを取得
    CGRect frame = self.itemScrollView.frame;
    // _scrollViewのフレームを現在のpageControlの値に合わせる
    frame.origin.x = frame.size.width * self.itemControll.currentPage;
    frame.origin.y = 0;
    // スクロールビューを現在の可視領域にスクロールさせる
    [self.itemScrollView scrollRectToVisible:frame animated:YES];
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGFloat pageWidth = self.itemScrollView.frame.size.width;
    self.itemControll.currentPage = floor((self.itemScrollView.bounds.origin.x - pageWidth / 2) / pageWidth ) + 1;

}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    int pageNum = self.itemScrollView.bounds.origin.x / self.itemScrollView.frame.size.width;
    return [self.view viewWithTag:pageNum + 1000];
}