Question

编辑 - 解决： 我为“Feed”添加了一个模型，它处理了我遇到的映射问题。谢谢！

我想在UITableView行中显示所有“标题”，但我遇到了崩溃：

WebListViewController.m -

@interface WebListViewController ()

@property (strong, nonatomic) NSArray *headlinesNow;

@end

@implementation WebListViewController

@synthesize tableView = _tableView;
@synthesize headlinesNow;

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSString *lAbbreviation = [defaults objectForKey:@"lAbbreviation1"];
    NSString *tID = [defaults objectForKey:@"tId1"];

 NSString *url = [NSString stringWithFormat:@"/now/?l=%@&t=%@&apikey=5xxxxxxxx", lAbbreviation, tID];
    [[RKObjectManager sharedManager] loadObjectsAtResourcePath:url usingBlock:^(RKObjectLoader *loader)  {
        loader.onDidLoadObjects = ^(NSArray *objects) {

headlinesNow = objects;

[_tableView reloadData];

[loader.mappingProvider setMapping:[Headline mapping] forKeyPath:@"feed.headline"];
        loader.onDidLoadResponse = ^(RKResponse *response){
            NSLog(@"BodyAsString: %@", [response bodyAsString]);
        };
    }];

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{

    return headlinesNow.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{

    static NSString *CellIdentifier = @"standardCell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    Headline *headlineLocal = [headlinesNow objectAtIndex:indexPath.row];
    NSString *headlineText = [NSString stringWithFormat:@"%@", headlineLocal.headline];
    cell.textLabel.text = headlineText;
    return cell;
}

Headline.h

@interface Headline : NSObject
@property (strong, nonatomic) NSString *headline;
@property (strong, nonatomic) Links *linksHeadline;
+ (RKObjectMapping *) mapping;
@end

Headline.m

@implementation Headline
+ (RKObjectMapping *)mapping {
    RKObjectMapping *objectMapping = [RKObjectMapping mappingForClass:[self class] usingBlock:^(RKObjectMapping *mapping) {
        [mapping mapKeyPathsToAttributes:
         @"headline", @"headline",
         nil];
        [mapping hasOne:@"links" withMapping:[Links mapping]];
    }];
    return objectMapping;
}
@end

JSON Response Body -

{
    "timestamp": "2013-05-03T22:03:45Z",
    "resultsOffset": 0,
    "status": "success",
    "resultsLimit": 10,
    "breakingNews": [],
    "resultsCount": 341,
    "feed": [{
        "headline": "This is the first headline",
        "lastModified": "2013-05-03T21:33:32Z",
        "premium": false,
        "links": {
            "api": {

我收到了NSLog的{{1}}输出，但程序崩溃了，没有填写bodyAsResponse。我显然没有正确导航到JSON？有什么想法吗？

感谢您的帮助，如果您需要更多代码段，请与我们联系 -

修改 - 崩溃是：由于未捕获的异常'NSUnknownKeyException'而终止应用程序，原因：'[＆lt; __ NSCFString 0xe693110＆gt; valueForUndefinedKey：]：此类不是关键标题的键值编码兼容。'

Answer 1

第一个问题是您当前的forKeyPath:@"feed.headline"。它应该只是forKeyPath:@"feed"，因为该密钥路径对您的JSON无效。原因是JSON中的feed是一个数组，因此它应映射到您的Headline对象，然后该对象的映射定义将用于headline。

下一期是linksHeadline属性和[mapping hasOne:@"links" withMapping:[Links mapping]];。键名不匹配。将Headline中的媒体资源名称更改为links。

UITableView没有正确地提取JSON

1 个答案: