在启用分页和滚动的情况下启用uiscrollview的缩放

我有一个uiscrollview，我加载了一系列图像，以便可以在图片中滚动，其效果类似于IOS中的图片效果。我正在使用此代码：

  NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    NSString *path = [paths objectAtIndex:0];
    NSString *imageFilePath = [path stringByAppendingPathComponent:@"newPics"];
    fileExists   = [[NSFileManager defaultManager] fileExistsAtPath:imageFilePath];
    if(fileExists){

        imgs=[[NSMutableArray  alloc]init];


    [imgs addObject:[UIImage imageWithContentsOfFile:[path stringByAppendingPathComponent:@"newPics/pic1.png"]]];
    [imgs addObject:[UIImage imageWithContentsOfFile:[path stringByAppendingPathComponent:@"newPics/pic2.png"]]];
    [imgs addObject:[UIImage imageWithContentsOfFile:[path stringByAppendingPathComponent:@"newPics/pic3.png"]]];
    [imgs addObject:[UIImage imageWithContentsOfFile:[path stringByAppendingPathComponent:@"newPics/pic4.png"]]];


    CGSize imageSize;
    imageSize.height = 648;
    imageSize.width = 927;
    self.scroll1.frame = CGRectMake(0,0,imageSize.width,imageSize.height);

    self.scroll1.contentSize = CGSizeMake(imageSize.width * imgs.count, imageSize.height );
    self.scroll1.minimumZoomScale=1.0;
    self.scroll1.maximumZoomScale=3.0;
    self.scroll1.pagingEnabled = YES;


    self.scroll1.delegate=self;

    CGFloat xPos = 0.0;

    for (UIImage *image in imgs) {
        imageView = [[UIImageView alloc] initWithImage:image];
        imageView.frame = CGRectMake(xPos, 0.0, imageSize.width, imageSize.height);
        [self.scroll1 addSubview:imageView];
        xPos += imageSize.width;

    }


    }

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    int positionScrollPrim = scrollView.contentOffset.x;

    int positionScroll = positionScrollPrim / 927 ;

    imageView = [[UIImageView alloc] initWithImage:[imgs objectAtIndex:positionScroll]];
    //UIImage *tmep =  [imgs objectAtIndex:1];

    return imageView;
}

我无法达到正确的结果，相反，我遇到一堆怪异的行为，例如错误的缩放和尝试缩放时不再滚动。我想我的问题出在viewForZoomingInScrollView部分，这就是为什么我尝试使用上述代码解决它的原因。但我只是无法使其工作。我想念什么？