NSJSONSerialization

Question

我对一些带有这种格式的服务的公共json服务有问题。

jsonFlickrFeed({
        "title": "Uploads from everyone",
        "link": "http://www.flickr.com/photos/",
        "description": "",
        "modifi ... })

NSJSONSerialization似乎无法让它的工作

NSURL *jsonUrl = [NSURL URLWithString:@"http://d.yimg.com/autoc.finance.yahoo.com/autoc?query=yahoo&callback=YAHOO.Finance.SymbolSuggest.ssCallback"];
NSError *error = nil;
NSData *jsonData = [NSData dataWithContentsOfURL:jsonUrl options:kNilOptions error:&error];
NSMutableDictionary *jsonResponse = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingAllowFragments error:&error];
NSLog(@"%@", jsonResponse);

Answer 1

使用最新的web API，我已经解决了我的问题。

作为参考，旧的web API为：http://api.flickr.com/services/feeds/photos_public.gne?id=xxxxxxxx&lang=en-us&format=json

当前的web API为：http://api.flickr.com/services/feeds/photos_public.gne?id=xxxxxxxx&lang=en-us&format=json&nojsoncallback=1

做完了，。

Answer 2

我认为NSJSONSerialization不能处理jsonFlickrFeed ( ... )在您的JSON代码中。问题是纯响应是无效的JSON (测试它here)。

因此，您必须构建一种解决此问题的方法。例如，您可以搜索字符串jsonFlickrFeed(在响应中将其删除)，或者-更简单的方法-只是在有效的JSON开始之前截断开头，并去掉最后一个字符(应该是括号)。

Answer 3

Flickr使用JSON做了一些解析器无法处理的坏事：

• 以'jsonFlickrFeed(‘’开头，以')‘结尾
  • 这意味着根对象不是valid

​

• 他们错误地转义单引号..例如：\‘
  • 这是无效的JSON，将使解析器成为JSON

​

对于那些希望处理Flick JSON提要的人

//get the feed
NSURL *flickrFeedURL = [NSURL URLWithString:@"http://api.flickr.com/services/feeds/photos_public.gne?format=json&tags=data"];
NSData *badJSON = [NSData dataWithContentsOfURL:flickrFeedURL];
//convert to UTF8 encoded string so that we can manipulate the 'badness' out of Flickr's feed
NSString *dataAsString = [NSString stringWithUTF8String:[badJSON bytes]];
//remove the leading 'jsonFlickrFeed(' and trailing ')' from the response data so we are left with a dictionary root object
NSString *correctedJSONString = [NSString stringWithString:[dataAsString substringWithRange:NSMakeRange (15, dataAsString.length-15-1)]];
//Flickr incorrectly tries to escape single quotes - this is invalid JSON (see http://stackoverflow.com/a/2275428/423565)
//correct by removing escape slash (note NSString also uses \ as escape character - thus we need to use \\)
correctedJSONString = [correctedJSONString stringByReplacingOccurrencesOfString:@"\\'" withString:@"'"];
//re-encode the now correct string representation of JSON back to a NSData object which can be parsed by NSJSONSerialization
NSData *correctedData = [correctedJSONString dataUsingEncoding:NSUTF8StringEncoding];
NSError *error = nil;
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:correctedData options:NSJSONReadingAllowFragments error:&error];
if (error) {
    NSLog(@"this still sucks - and we failed");
} else {
    NSLog(@"we successfully parsed the flickr 'JSON' feed: %@", json);
}

故事的寓意- Flickr是淘气的-扇。