Question

我目前有一个包含大量图像网址的数组，名为images它们会被放入我的表格中：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *simpleTableIdentifier = @"SimpleTableCell";

    SimpleTableCell *cell = (SimpleTableCell *)[tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier];
    if (cell == nil)
    {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"SimpleTableCell" owner:self options:nil];
        cell = [nib objectAtIndex:0];
    }

    NSLog(@"indexPath.row=%ld", (long)indexPath.row);
    NSLog(@"images[indexPath.row]=%@", [images objectAtIndex:indexPath.row]);

    NSString *stringy = @"http://www.tragicclothing.co.uk/";
    NSString *link = [stringy stringByAppendingString: images[indexPath.row]];
    NSString* encodedString = [link stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    NSData * imageData = [[NSData alloc] initWithContentsOfURL: [NSURL URLWithString:encodedString]];
    cell.thumbnailImageView.image = [UIImage imageWithData: imageData];
    cell.backgroundColor = [UIColor clearColor];
    cell.opaque = NO;
    cell.backgroundView = nil;

    return cell;
}

但这会在滚动时造成很多延迟。我怎么能缓存数据？防止这种滞后？我见过SDWebImage但我不太清楚如何使用它！这看起来很复杂。

我应该使用

SDImageCache *imageCache = [[SDImageCache alloc] initWithNamespace:@"myNamespace"];
[imageCache queryDiskCacheForKey:myCacheKey done:^(UIImage *image)
{
    // image is not nil if image was found
}];

Answer 1

没有什么比SDWebImage

更简单

它促进了以下解决方案

UIImageView类别，将Web图像和缓存管理添加到Cocoa Touch框架

异步图片下载器

具有自动缓存到期处理的异步内存+磁盘映像缓存

#import <SDWebImage/UIImageView+WebCache.h>

NSString* encodedString = [link stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

[cell.thumbnailImageView setImageWithURL:[NSURL URLWithString:encodedString]
               placeholderImage:[UIImage imageNamed:@"placeholder.png"]];

Answer 2

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *simpleTableIdentifier = @"SimpleTableCell";

    SimpleTableCell *cell = (SimpleTableCell *)[tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier];
    if (cell == nil)
    {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"SimpleTableCell" owner:self options:nil];
        cell = [nib objectAtIndex:0];
    }

    NSLog(@"indexPath.row=%ld", (long)indexPath.row);
    NSLog(@"images[indexPath.row + 7]=%@", [images objectAtIndex:indexPath.row + 7]);


    NSString *stringy = @"http://www.tragicclothing.co.uk/";
    NSString *link = [stringy stringByAppendingString: images[indexPath.row + 7]];
    NSString* encodedString = [link stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    [cell.thumbnailImageView setImageWithURL:[NSURL URLWithString:encodedString] placeholderImage:[UIImage imageNamed:@"Comp 2_00000.png"]];
    cell.backgroundColor = [UIColor clearColor];
    cell.opaque = NO;
    cell.backgroundView = nil;


    return cell;
}

如何缓存图像ios

2 个答案: