如何从 Web 服务获取 JSON 数据？ iOS 目标-c

Question

我现在找不到有用的示例。我的服务器上有一个 php 脚本，它从选定的数据库表中返回所有数据。我正在尝试从我的客户端 ios 设备中获取它并解析该 json，以便我可以查看那里的内容并将其中一些数据添加到我的 sqlite 数据库中。我现在正在使用 fmdb 作为包装器。这是我连接到服务器的代码，我不确定从那里去哪里

  NSURL *url = [NSURL URLWithString:@"http://index.php"];

NSString * post =[NSString stringWithFormat:@"lang=%@",@"English"];

NSData *postData = [post dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];
NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]];

NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
[request setTimeoutInterval:60];

[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];

NSURLConnection* connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
[connection start];

我的json数据是这样的

{"login":[{"userid":"1","password":"test","aclevel":"1"}],"answers":[{"aid":"1","qid":"1","sid":"1","freetext":null,"a":null,"b":null,"c":null,"d":null,"e":null,"f":null,"g":null,"h":null,"i":null,"j":null,"synch":null,"type":null},{"aid":"5","qid":"5","sid":"5","freetext":null,"a":null,"b":null,"c":null,"d":null,"e":null,"f":null,"g":null,"h":null,"i":null,"j":null,"synch":null,"type":null}],"projects":{"pid":"3","name":"apmatt","descr":"tapest","creator":"macurlatt","datetime":null,"synch":null},"questions":[{"qid":"1","pid":"1","sid":"1","question":null,"a":null,"b":null,"c":null,"d":null,"e":null,"f":null,"g":null,"h":null,"i":null,"j":null,"synch":null,"type":null}],"surveys":[{"sid":"2","pid":"2","name":"matt","descr":"test","creator":"matt","datetime":null,"synch":null},{"sid":"3","pid":"3","name":"amatt","descr":"taest","creator":"maatt","datetime":null,"synch":null}]}

Answer 1

如果您确定服务器返回的 JSON 非常有效，那就很简单了。 iOS 提供了NSJSONSerialization 类来让你实现这一点。以下代码行让您了解该过程：

__block id data = nil;
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue currentQueue]
                       completionHandler:^(NSURLResponse*       response, NSData* responseData, NSError* err) {
    data = [NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingMutableContainers error:nil];
}];

如果响应采用有效的 JSON 格式，您可以将数据返回到“data”变量中，根据数据的格式，该变量可以是 NSArray 或 NSDictionary，它已被解析。