Question

我有tableView，需要从URL加载图片。我有一个包含图像URL的数组，当页面加载时我需要将所有图像加载到tableview中。请注意，不是来自单个URL，而是具有不同URL的数组。我该如何实现呢？请帮忙

感谢。

Answer 1

您可以使用GCD在后台线程中加载图像，如下所示：

//get a dispatch queue
dispatch_queue_t concurrentQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    //this will start the image loading in bg
    dispatch_async(concurrentQueue, ^{        
        NSData *image = [[NSData alloc] initWithContentsOfURL:imageURL];

        //this will set the image when loading is finished
        dispatch_async(dispatch_get_main_queue(), ^{
            imageView.image = [UIImage imageWithData:image];
        });
    });

您好。但是你可能需要添加一个dispatch_release（concurrentQueue）;确保没有泄漏。 - 弗兰克8月25日19:43

Answer 2

如果您想从互联网下载图片

，可以使用延迟加载

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
   //All you reusable cell implementation here.
   //Since your Images sizes differ. Keep a custom Imageview

    if(![imagesForCategories containsObject:indexPath])
    {    
        customImageView.image = [UIImage imageNamed:@"default-image.png"];
        NSMutableArray *arr = [[NSArray alloc] initWithObjects:[imageUrlArray objectAtIndex:indexPath.row],indexPath, nil];
        [self performSelectorInBackground:@selector(loadImageInBackground:) withObject:arr];
        [arr release];
    }
    return cell;
}

- (void) loadImageInBackground:(NSArray *)urlAndTagReference 
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    NSURL *imgUrl=[[NSURL alloc] initWithString:[urlAndTagReference objectAtIndex:0]];
    NSData *imgData = [NSData dataWithContentsOfURL:imgUrl];
    UIImage *img = [UIImage imageWithData:imgData];
    [imgUrl release]; 
    NSMutableArray *arr = [[NSMutableArray alloc ] initWithObjects:img,[urlAndTagReference objectAtIndex:1], nil  ];
    [self performSelectorOnMainThread:@selector(assignImageToImageView:) withObject:arr waitUntilDone:YES];
    [arr release];
    [pool release];
}

- (void) assignImageToImageView:(NSMutableArray *)imgAndTagReference
{
    [imagesForCategories addObject:[imgAndTagReference objectAtIndex:1]];
    UITableViewCell *cell = [celebCategoryTableView cellForRowAtIndexPath:[imgAndTagReference objectAtIndex:1]];
    UIImageView *profilePic = (UIImageView *)[cell.contentView viewWithTag:20];
    profilePic.image = [imgAndTagReference objectAtIndex:0];

}

Answer 3

您可以使用SDWebImage，它可以在UITableView中轻松快速地加载图像 https://github.com/rs/SDWebImage

Answer 4

尝试此代码，imagearray包含图片网址

-(UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSData* imageData = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString: [imagearray objectAtIndex:row]]];
    UIImage* image = [[UIImage alloc] initWithData:imageData];


    cell.imageView.image =image;
    return cell;
}

Answer 5

您需要为延迟加载创建自定义单元格。这将允许您正确下载图像，而不会冻结。这是一个很好的例子，如何做到这一点： Asynch image loading

Answer 6

使用afnetworki，太容易了。

//afnetworking

#import "UIImageView+AFNetworking.h"

 [cell.iboImageView setImageWithURL:[NSURL URLWithString:server.imagen] placeholderImage:[UIImage imageNamed:@"qhacer_logo.png"]];

从URL iphone sdk将图像加载到tableView

6 个答案: