Question

我有一个幻灯片显示，可以从数据库中收集一系列图像。每个图像都有描述和与之关联的其他属性。基本上我想在每次加载新图像时更新UILabel的文本。我怎样才能做到这一点？

以下是我的工作内容：

 //SLIDE MENU
- (void)loadVisiblePages {
    // First, determine which page is currently visible
    CGFloat pageWidth = gridView.frame.size.width;
    NSInteger page = (NSInteger)floor((gridView.contentOffset.x * 2.0f + pageWidth) / (pageWidth * 2.0f));
    //NSArray * descriptArray[20];

    // Update the page control
    pageControl.currentPage = page;

    // Work out which pages you want to load
    NSInteger firstPage = page - 1;
    NSInteger lastPage = page + 1;

    // Purge anything before the first page
    for (NSInteger i=0; i<firstPage; i++) {
        [self purgePage:i];
    }
    for (NSInteger i=firstPage; i<=lastPage; i++) {
        [self loadPage:i];
        // descriptArray[i] = selectedPhotoDesc;
    }
    for (NSInteger i=lastPage+1; i<self.pageImages.count; i++) {
        [self purgePage:i];
    }
}


- (void)loadPage:(NSInteger)page {
    NSURL* imageURL = [NSURL URLWithString:[NSString stringWithFormat:@"%@%@%@/%@.jpg", host, photoPath, collection, photoNumber]];

    //get photo from server
    NSData *imageData = [[NSData alloc] initWithContentsOfURL:imageURL];
    UIImage *image = [[UIImage alloc] initWithData: imageData];

    if (page < 0 || page >= 20) {
        return;
    }

    // Load an individual page, first checking if you've already loaded it
    UIView *pageView = [self.pageViews objectAtIndex:page];
    if ((NSNull*)pageView == [NSNull null]) {
        CGRect frame = gridView.bounds;
        frame.origin.x = frame.size.width * page;
        frame.origin.y = 0.0f;
        frame = CGRectInset(frame, 10.0f, 0.0f);
        UIImageView *newPageView = [[UIImageView alloc] initWithImage:image];
        newPageView.frame = frame;
        [gridView addSubview:newPageView];
        labelDescription.text = descriptionArray[page];
        [self.pageViews replaceObjectAtIndex:page withObject:newPageView];
    }
}

- (void)purgePage:(NSInteger)page {
    if (page < 0 || page >= self.pageImages.count) {
        // If it's outside the range of what you have to display, then do nothing
        return;
    }

// Remove a page from the scroll view and reset the container array
UIView *pageView = [self.pageViews objectAtIndex:page];
if ((NSNull*)pageView != [NSNull null]) {
    [pageView removeFromSuperview];
    [self.pageViews replaceObjectAtIndex:page withObject:[NSNull null]];
    labelDescription.text = @"";
}
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    // Load the pages that are now on screen
    [self loadVisiblePages];
}

我应该提一下，我可以滑动不同的图像，但无法更新文本。就目前而言，我只能获得与第一张图片相对应的文字而不是其他内容。致谢

更新UIlabel的文本

0 个答案: