Question

我正在UItableViewCell中从服务器加载图像。

由于每个图像占用10MB大小会导致内存问题。应用程序崩溃只要我滚动tableView

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    locationcellObject=[self.tableView dequeueReusableCellWithIdentifier:@"cell" forIndexPath:indexPath];
    NSDictionary *temp= [sortedArray objectAtIndex:indexPath.row];
    locationcellObject.title.text=[temp objectForKey:@"locationtitle"];
    locationcellObject.subtitle_Lbl.text=[temp objectForKey:@"category"];
    NSString *trimmedtitle = [[temp objectForKey:@"locationtitle"]stringByReplacingOccurrencesOfString:@" " withString:@""];
    NSString *name=[NSString stringWithFormat:@"images/%@.png",trimmedtitle];
    NSString *imageName=[NSString stringWithFormat:@"http://my_URL_HERE/%@",name];
    _tempData = [NSData dataWithContentsOfURL:[NSURL URLWithString:imageName]];
    UIImage *display=[[UIImage alloc]initWithData:_tempData];
    locationcellObject.locationPic_img_View.image=display;
    locationcellObject.locationPic_img_View.contentMode=UIViewContentModeScaleAspectFit;

    return locationcellObject;
}

有没有简单的方法可以做到？

Answer 1

1）你应该在后台进行下载
2）制作图像的缩略图（尺寸较小的图像）

 dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0),^ {
_tempData = [NSData dataWithContentsOfURL:[NSURL URLWithString:imageName]];
UIImage *display=[[UIImage alloc]initWithData:_tempData];

//make a thumbnail of the image 

UIImage *display; 
CGSize destinationSize = ...;
UIGraphicsBeginImageContext(destinationSize);
[originalImage drawInRect:CGRectMake(0,0,destinationSize.width,destinationSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
//
dispatch_async(dispatch_get_main_queue(), ^{
//put result to main thread
locationcellObject.locationPic_img_View.image= newImage;
     });
});

Answer 2

在后台线程中下载图像，在块中下载图像。通过这种方式，两个线程将在您的应用程序主线程和后台线程中运行。它将减少主线程的负载。

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

    //Call your function or whatever work that needs to be done
    //Code in this part is run on a background thread

    dispatch_async(dispatch_get_main_queue(), ^(void) {

        //Stop your activity indicator or anything else with the GUI
        //Code here is run on the main thread

    });
});

还可以使用NSCache将下载的图像添加到缓存中，下次从缓存加载图像时

您可以在此处查看此link，您可以在此找到如何在缓存中添加图片

Answer 3

请参阅THIS教程。它描述了以有效的方式在UItableView中获取/加载图像。

内存在UITableviewcell中加载图像时出现问题？

3 个答案: