如何从json响应中获取图像并在集合视图ios中显示

Question

我是 iOS 新手，我从 json 获取图像 url。现在我想在集合视图上显示它。我正在做下面的代码。但无法在集合视图中显示图像。有人可以帮我解决这个问题吗？enter code here

// 集合查看代码

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    return 1;
}

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{

    return imageArray.count;
}

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{

    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cellIdentifier" forIndexPath:indexPath];

    if(!cell)
    {
        cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cellIdentifier" forIndexPath:indexPath];
        UIImageView *myImageView = [[UIImageView alloc]initWithFrame:CGRectMake(50,0, 50, 80)];
        myImageView.tag = 101;
        [cell.contentView addSubview:myImageView];
    }


    NSString *myImage = [imageArray objectAtIndex:indexPath.row];

    NSString *ImageString = [myImage stringByReplacingOccurrencesOfString:@"" withString:@"%20"];

    NSLog(@"Image String %@",ImageString);

    NSURL *imageURL = [NSURL URLWithString:ImageString];

    NSData *imageData = [NSData dataWithContentsOfURL:imageURL];

    UIImageView *img = (UIImageView*)[cell.contentView viewWithTag:101];
    img.backgroundColor = [UIColor redColor ];

    cell.backgroundView = [UIImage imageWithData:imageData];

    return cell;

}

// Json 服务

NSDictionary *get = @{@"uid":[uidSave valueForKey:@"uid"],@"pro":proNumber};
        NSLog(@"Dictionary Data which is to be get %@",get);

        NSData* jsonData = [NSJSONSerialization dataWithJSONObject:get options:kNilOptions error:nil];
        NSString *jsonInputString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
        NSString *post = [[NSString alloc]initWithFormat:@"r=%@",jsonInputString];

        NSURL *url=[NSURL URLWithString:[NSString stringWithFormat:@"%@",displayCaseUrl]];

        NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
        NSString *postLength = [NSString stringWithFormat:@"%lu", (unsigned long)[postData length]];
        NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:120.0];
        [request setURL:url];
        [request setHTTPMethod:@"POST"];
        [request setValue:postLength forHTTPHeaderField:@"Content-Length"];
        [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
        [request setHTTPBody:postData];

        NSError *error;
        NSURLResponse *response;
        NSData *responseData=[NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
        if (responseData != nil)
        {
            jsonDict = (NSMutableDictionary *)[NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];
            NSLog(@"Values =======%@",jsonDict);

            NSMutableDictionary *imageDict = [jsonDict valueForKey:@"images"];
            NSLog(@"Image Dictionary :- %@",imageDict);
            imageArray = [imageDict valueForKey:@"image_url"];
            NSLog(@"MY Array Image :- %@",imageArray);

// 要获取图像的 Json 响应

Image Dictionary :- (
        {
        "image_url" = "http://zapponomics.net/claimservice/parcelimage/1486154806image0.jpg";
        "img_for" = "Front view of parcel";
        "pro_number" = orange;
    }
)
2015-08-26 10:09:05.806 ClaimCloud[1997:87342] MY Array String :- (
    "http://zapponomics.net/claimservice/parcelimage/1486154806image0.jpg"
)

//////// USIng 像这样但是不行

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{

    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cellIdentifier" forIndexPath:indexPath];
    UIImageView *myImageView = [[UIImageView alloc]initWithFrame:CGRectMake(50,0, 50, 80)];
    myImageView.tag = 101;
    [cell.contentView addSubview:myImageView];
    NSString *myImage = [imageArray objectAtIndex:indexPath.row];
   [self loadImageFromURL:[NSURL URLWithString:[myImage stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]] callback:^(UIImage *image) {
        myImageView.image = image;
    }];
    return cell;
}

- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
    return UIEdgeInsetsMake(0, 0, 0,200);

}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
    return CGSizeMake(100,80);

}
- (void) loadImageFromURL: (NSURL*) url callback:(void (^)(UIImage *image))callback {
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
    dispatch_async(queue, ^{
        NSData * imageData = [NSData dataWithContentsOfURL:url];
        dispatch_async(dispatch_get_main_queue(), ^{
            UIImage *image = [UIImage imageWithData:imageData];
            callback(image);
        });
    });
}

Answer 1

有一个非常好的库，名为SDWebImage，它可以帮助您从 URL 加载图像。如上述@poojathorat 的回答，如果图像尺寸较大，您将图像转换为数据，而不是你会遇到内存问题，但是这个库也会管理内存。所以我认为使用这个库。

只需拖动项目中的 SDWebImage 文件夹并导入

#import "UIImageView+WebCache.h"

然后使用此方法从 URL 加载图像

[cell.imageView sd_setImageWithURL:[NSURL URLWithString:@"http://www.domain.com/path/to/image.jpg"]placeholderImage:[UIImage imageNamed:@"placeholder.png"]];

它还将管理图像的缓存。

如果您不想包含库，请使用此功能

- (void) loadImageFromURL: (NSURL*) url callback:(void (^)(UIImage *image))callback {
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
    dispatch_async(queue, ^{
        NSData * imageData = [NSData dataWithContentsOfURL:url];
        dispatch_async(dispatch_get_main_queue(), ^{
            UIImage *image = [UIImage imageWithData:imageData];
            callback(image);
        });
    });
}

并像这样使用这个函数

[self loadImageFromURL:[NSURL URLWithString:["yourURL" stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]] callback:^(UIImage *image) {
    yourImageView.image = image;
}]

Answer 2

不用%20替换空格，按照以下方式直接申请。

NSString *myImage = [imageArray objectAtIndex:indexPath.row];
NSURL *url = [NSURL URLWithString:myImage];
NSData *data = [NSData dataWithContentsOfURL:url];
UIImage *image = [UIImage imageWithData:data];
cell. myImageView.image = [UIImage imageNamed:img];