如何在iOS中使用AFNetworking從緩存加載數據？

Question

我正在使用AFNetworking庫來調用Web服務。 我的應用程序在集合視圖單元格和表視圖單元格中具有圖像視圖。 每次加載我的應用程序時，都會花費大量時間來加載圖像。 所以我想從緩存中加載圖像的方法。 我已經附加了部分代碼。

- (void)loadcategoryData
{
    post = nil;
    NSString *mainurl = [NSString stringWithFormat:@"some url"];
    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];

    manager.responseSerializer.acceptableContentTypes = [manager.responseSerializer.acceptableContentTypes setByAddingObject:@"text/html"];
    [manager GET:mainurl parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {

        posts = (NSDictionary *)responseObject;
        post = [NSMutableArray array];
        for(NSDictionary *all in posts)
        {
            Categories *category = [Categories new];
            category.title = [all objectForKey:@"catname"];
            category.firsturl = [all objectForKey:@"url"];

            [self.maincollectionView reloadData];
            //call for images

            imagespost = nil;
            NSString *imageUrl = [NSString stringWithFormat:@"%@", category.firsturl];
            AFHTTPRequestOperationManager *managerone = [AFHTTPRequestOperationManager manager];
            [managerone GET:imageUrl parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {

                imagesposts = (NSDictionary *)responseObject;
                NSArray *resultone = [imagesposts objectForKey:@"posts"];
                imagespost = [NSMutableArray array];
                if ([resultone count]) {
                    NSDictionary *firstpost = resultone[0];
//                    Categories *newmogocat = [Categories new];

                    NSDictionary *thumbnail_images = [firstpost objectForKeyedSubscript:@"thumbnail_images"];
                    NSDictionary *thumbnail = [thumbnail_images objectForKey:@"thumbnail"];
                    category.imageOneUrl = [NSString stringWithFormat:@"%@",[thumbnail objectForKey:@"url"]];
//                    NSLog(@"%@", newmogocat.imageOneUrl);
//                    [imagespost addObject:newmogocat];

                    [post addObject:category];

                    [self.maincollectionView reloadData];
                }

            } failure:^(AFHTTPRequestOperation *operation, NSError *error) {

                UIAlertView *erroralert = [[UIAlertView alloc] initWithTitle:@"Something Wrong!" message:[NSString stringWithFormat:@"%@", error.localizedDescription] delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
                [erroralert show];

            }];                                
        }

    } failure:^(AFHTTPRequestOperation *operation, NSError * responseObject) {

    }];
}

- (NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse
{
    NSMutableDictionary *mutableUserInfo = [[cachedResponse userInfo] mutableCopy];
    NSMutableData *mutableData = [[cachedResponse data] mutableCopy];
    NSURLCacheStoragePolicy storagePolicy = NSURLCacheStorageAllowedInMemoryOnly;

    return [[NSCachedURLResponse alloc] initWithResponse:[cachedResponse response] data:mutableData userInfo:mutableUserInfo storagePolicy:storagePolicy];
}

---

這是返回單元格

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    CategoryCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cellidentifier" forIndexPath:indexPath];
//    cell.layer.borderWidth = 2.0f;
    cell.layer.masksToBounds = NO;
    cell.layer.cornerRadius = 5.0;
    cell.layer.borderColor = [UIColor lightGrayColor].CGColor;
    cell.layer.shadowOffset = CGSizeMake(0, 1);
    cell.layer.shadowRadius = 4.0;
    cell.layer.shadowColor = [UIColor darkGrayColor].CGColor;

    [cell addSubview:cell.maintitleLabel];

    Categories *cat = [post objectAtIndex:indexPath.row];
    [self.maincollectionView reloadInputViews];
    cell.maintitleLabel.text = [NSString stringWithFormat:@" %@ ", cat.title];
    [cell.maintitleLabel sizeToFit];               

    NSString *mainstring = [NSString stringWithFormat:@"%@", cat.imageOneUrl];
    NSURL *url = [NSURL URLWithString:mainstring];
//
    [cell.mainImageView setImageWithURL:url placeholderImage:nil];
//

    return cell;
}

Answer 1

您需要的是一個單獨的類。 此類的每個對象都知道如何異步下載單個圖像，並將其緩存並通知與之關聯的圖像視圖該圖像已准備好顯示...

幸運的是AFNetworking已經為您編寫了此內容。 檢出其對UIImageView的擴展。 使用此擴展，您只需將圖像的URL傳遞到UIImageView（帶有setImageWithURL ），它就會為您完成所有艱苦的工作。

https://github.com/AFNetworking/AFNetworking/blob/master/UIKit%2BAFNetworking/UIImageView%2BAFNetworking.h

對於不使用AFNetworking的用戶，Apple提供了示例代碼： https : //developer.apple.com/library/ios/samplecode/LazyTableImages/Introduction/Intro.html