Question

我正在尝试实现像facebook或Twitter时间轴这样的表格。但是当我滚动UITableView时，它非常缓慢且滞后。我该如何解决这个问题？

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    ViewControllerCell *cell = [tableView dequeueReusableCellWithIdentifier:@"htrcell"];
    if (cell==nil)
    {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"Cell" owner:self options:nil];
        cell = [nib objectAtIndex:0];
    }

    NSDictionary *dataArray = [self.threndsArray objectAtIndex:indexPath.row];

    NSURL *url = [NSURL URLWithString:[dataArray objectForKey:@"pic_timeline"]];

    NSData *imgData = [NSData dataWithContentsOfURL:url];

    cell.upload_image.image =[UIImage imageWithData:imgData];

    NSURL *urlimage = [NSURL URLWithString:[dataArray objectForKey:@"pic_user"]];
    NSData *Dataimage = [NSData dataWithContentsOfURL:urlimage];
    cell.uploder_image.image =[UIImage imageWithData:Dataimage];
    cell.uploder_image.clipsToBounds = YES;
    cell.uploder_image.layer.cornerRadius = cell.uploder_image.frame.size.height /2;
    cell.uploder_image.layer.borderWidth = 2.0;
    cell.uploder_image.layer.borderColor = [UIColor whiteColor].CGColor;

    cell.uploder_name.text=[dataArray valueForKeyPath:@"nama_user"];

    cell.like_counter.text=[NSString stringWithFormat:@"%@",[dataArray valueForKeyPath:@"likes"]];

    cell.commenter_name.text=[dataArray valueForKeyPath:@"status_timeline"];

    cell.comments.text=[dataArray valueForKeyPath:@"tgl_timeline"];


    [cell setSelectionStyle:UITableViewCellSelectionStyleNone];

    return  cell;
}

Answer 1

主要问题是，您在主线程中将图片网址转换为/usr/bin/codesign，这就是延迟滚动发生的原因。您需要将后台队列中的图像URL转换为NSData并更新主队列中的UI。

这样你就可以在后台加载每个图像，加载后相应的单元格会在mainThread上更新。

以下代码可以帮助您

NSData

Answer 2

您也可以尝试NSURLRequest

NSURL *url = [NSURL URLWithString:[dataArray objectForKey:@"pic_timeline"]];

NSURLRequest *request = [NSURLRequest requestWithURL:url];

[NSURLConnection sendAsynchronousRequest:request
                 queue:[NSOperationQueue mainQueue]
                 completionHandler:^(NSURLResponse * response,
                 NSData * data, NSError * error) 
{

    if (!error) {

        cell.upload_image.image = [UIImage imageWithData:data];

    }
}

Answer 3

如果您使用某些URL加载图片，那么最好的方法是加载图片Asynchronously。因此，我建议您查看以下链接以加载图片Asynchronously

Answer 4

由于图像尺寸大而发生这种情况。 1.在不降低后端质量的情况下，将图像尺寸减小到（低于200 kb） 2.在背景中下载图像

NSURLSessionDownloadTask *downloadPhotoTask = [[NSURLSession sharedSession]
                                                   downloadTaskWithURL:[NSURL URLWithString:@"Your_URL"] completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) {
                            UIImage *downloadedImage = [UIImage imageWithData:[NSData dataWithContentsOfURL:location]];

                                                       dispatch_async(dispatch_get_main_queue(), ^{
                                                           downloadAllImageview.image=downloadedImage;
                                                           [activityIndicator stopAnimating];
                                                           [activityIndicator removeFromSuperview];
                                                       });

                                                   }];

    [downloadPhotoTask resume];

Answer 5

最好的方法是SDWebImageView 下载并使用像贝娄一样：

导入.h

中的2个文件

#import "SDWebImage/UIImageView+WebCache.h"
#import "UIImageView+UIActivityIndicatorForSDWebImage.h"

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    ViewControllerCell *cell = [tableView dequeueReusableCellWithIdentifier:@"htrcell"];
    if (cell==nil)
    {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"Cell" owner:self options:nil];
        cell = [nib objectAtIndex:0];
    }
    NSDictionary *dataArray = [self.threndsArray objectAtIndex:indexPath.row];

    NSURL *url = [NSURL URLWithString:[dataArray objectForKey:@"pic_timeline"]];

    [cell.upload_image setImageWithURL:[dataArray objectForKey:@"pic_timeline"] placeholderImage:nil usingActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];

    cell.uploder_image.clipsToBounds = YES;
    cell.uploder_image.layer.cornerRadius =       cell.uploder_image.frame.size.height /2;
    cell.uploder_image.layer.borderWidth = 2.0;
    cell.uploder_image.layer.borderColor = [UIColor whiteColor].CGColor;


    cell.uploder_name.text=[dataArray valueForKeyPath:@"nama_user"];

    cell.like_counter.text=[NSString stringWithFormat:@"%@",[dataArray valueForKeyPath:@"likes"]];

    cell.commenter_name.text=[dataArray valueForKeyPath:@"status_timeline"];

    cell.comments.text=[dataArray valueForKeyPath:@"tgl_timeline"];


    [cell setSelectionStyle:UITableViewCellSelectionStyleNone];

    return  cell;
}

Answer 6

Please Try SDWebimage Library or download image Asynchronous

If you using SDWebimage please try this method:-

[imageView sd_setImageWithURL:[NSURL URLWithString:@"https://graph.facebook.com/olivier.poitrey/picture"]
             placeholderImage:[UIImage imageNamed:@"avatar-placeholder.png"]
                      options:SDWebImageRefreshCached];

Answer 7

缓慢加载可能是因为您放置了大量数据对象。您可以使用一些缓存库或执行objective-C通过NSCache类提供的缓存。您可以做的另一件事是在项目中使用Facebook提供的ComponentKit库。

缓存库：

FastImageCache

SDWebImage

时间线图书馆：

Facebook's Component Kit

滚动时TableView滞后

7 个答案: