使用NSURLSession获取JSON数据

Question

我试图使用NSURLSession从谷歌距离api获取数据,但如下所示,当我打印响应和数据时,我得到的结果为NULL.可能是什么问题？或者是否有任何其他更好的方法来获取JSON数据.

NSString *urlAsString = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/distancematrix/json?origins=Vancouver+BC|Seattle&destinations=San+Francisco|Victoria+BC&mode=bicycling&language=fr-FR&key=API-KEY"];

NSURL *url = [NSURL URLWithString:urlAsString];


NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];

[[session dataTaskWithURL:[NSURL URLWithString:urlAsString]
            completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

                NSLog(@"RESPONSE: %@",response);
                NSLog(@"DATA: %@",data);


            }] resume];

Answer 1

你应该stringByAddingPercentEscapesUsingEncoding:在你的url字符串上使用,这就是你没有得到响应的原因:服务器返回了一个错误.

你应该检查error;)

我在URL字符串中替换了您的API密钥,如果您复制/粘贴我的代码,请记得自己放置:)

NSString *urlAsString = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/distancematrix/json?origins=Vancouver+BC|Seattle&destinations=San+Francisco|Victoria+BC&mode=bicycling&language=fr-FR&key=YOUR-API-KEY"];

NSCharacterSet *set = [NSCharacterSet URLQueryAllowedCharacterSet];
NSString *encodedUrlAsString = [urlAsString stringByAddingPercentEncodingWithAllowedCharacters:set];

NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];

[[session dataTaskWithURL:[NSURL URLWithString:encodedUrlAsString]
        completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {

    NSLog(@"RESPONSE: %@",response);
    NSLog(@"DATA: %@",data);

    if (!error) {
        // Success
        if ([response isKindOfClass:[NSHTTPURLResponse class]]) {
            NSError *jsonError;
            NSDictionary *jsonResponse = [NSJSONSerialization JSONObjectWithData:data options:0 error:&jsonError];

            if (jsonError) {
                // Error Parsing JSON

            } else {
                // Success Parsing JSON
                // Log NSDictionary response:
                NSLog(@"%@",jsonResponse);
            }
        }  else {
            //Web server is returning an error
        }
    } else {
        // Fail
        NSLog(@"error : %@", error.description);
    }
}] resume];