谈谈iOS开发之JSON格式数据的生成与解析

{"firstName":"Brett","lastName":"McLaughlin","email":"aaaa"} 

{  "programmers": [{    "firstName": "Brett",    "lastName": "McLaughlin",    "email": "aaaa"  }, {    "firstName": "Elliotte",    "lastName": "Harold",    "email": "cccc"  }],  "authors": [{    "firstName": "Isaac",    "lastName": "Asimov",    "genre": "sciencefiction"  }, {    "firstName": "Frank",    "lastName": "Peretti",    "genre": "christianfiction"  }],  "musicians": [{    "firstName": "Eric",    "lastName": "Clapton",    "instrument": "guitar"  }, {    "firstName": "Sergei",    "lastName": "Rachmaninoff",    "instrument": "piano"  }]}

// 如果数组或者字典中存储了 NSString, NSNumber, NSArray, NSDictionary, or NSNull 之外的其他对象,就不能直接保存成文件了.也不能序列化成 JSON 数据.  NSDictionary *dict = @{@"name" : @"me", @"do" : @"something", @"with" : @"her", @"address" : @"home"};    // 1.判断当前对象是否能够转换成JSON数据.  // YES if obj can be converted to JSON data, otherwise NO  BOOL isYes = [NSJSONSerialization isValidJSONObject:dict];    if (isYes) {    NSLog(@"可以转换");        /* JSON data for obj, or nil if an internal error occurs. The resulting data is a encoded in UTF-8.     */    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dict options:0 error:NULL];        /*     Writes the bytes in the receiver to the file specified by a given path.     YES if the operation succeeds, otherwise NO     */    // 将JSON数据写成文件    // 文件添加后缀名: 告诉别人当前文件的类型.    // 注意: AFN是通过文件类型来确定数据类型的!如果不添加类型,有可能识别不了! 自己最好添加文件类型.    [jsonData writeToFile:@"/Users/SunnyBoy/Sites/JSON_XML/dict.json" atomically:YES];        NSLog(@"%@", [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding]);      } else {        NSLog(@"JSON数据生成失败，请检查数据格式");      }

　　 NSArray *array = @[@"qn", @18, @"ya", @"wj"];    BOOL isYes = [NSJSONSerialization isValidJSONObject:array];    if (isYes) {    NSLog(@"可以转换");        NSData *data = [NSJSONSerialization dataWithJSONObject:array options:0 error:NULL];        [data writeToFile:@"/Users/SunnyBoy/Sites/JSON_XML/base" atomically:YES];    } else {        NSLog(@"JSON数据生成失败，请检查数据格式");      }

//使用TouchJson来解析北京的天气//获取API接口NSURL *url = [NSURL URLWithString:@"http://m.weather.com.cn/data/101010100.html"];//定义一个NSError对象，用于捕获错误信息NSError *error;NSString *jsonString = [NSString stringWithContentsOfURL:url encoding:NSUTF8StringEncoding error:&error];NSLog(@"jsonString--->%@",jsonString);//将解析得到的内容存放字典中，编码格式为UTF8，防止取值的时候发生乱码NSDictionary *rootDic = [[CJSONDeserializer deserializer] deserialize:[jsonString dataUsingEncoding:NSUTF8StringEncoding] error:&error];//因为返回的Json文件有两层，去第二层内容放到字典中去NSDictionary *weatherInfo = [rootDic objectForKey:@"weatherinfo"];NSLog(@"weatherInfo--->%@",weatherInfo);//取值打印NSLog(@"%@",[NSString stringWithFormat:@"今天是 %@ %@ %@ 的天气状况是：%@ %@ ",[weatherInfo objectForKey:@"date_y"],[weatherInfo objectForKey:@"week"],[weatherInfo objectForKey:@"city"], [weatherInfo objectForKey:@"weather1"], [weatherInfo objectForKey:@"temp1"]]);

//使用SBJson解析北京的天气NSURL *url = [NSURL URLWithString:@"http://www.weather.com.cn/adat/sk/101010100.html"];NSError *error = nil;NSString *jsonString = [NSString stringWithContentsOfURL:url encoding:NSUTF8StringEncoding error:&error];SBJsonParser *parser = [[SBJsonParser alloc] init];NSDictionary *rootDic = [parser objectWithString:jsonString error:&error];NSDictionary *weatherInfo = [rootDic objectForKey:@"weatherinfo"];NSLog(@"%@", [NSString stringWithFormat:@"今天是 %@ %@ %@ 的天气状况是：%@ %@ ",[weatherInfo objectForKey:@"date_y"],[weatherInfo objectForKey:@"week"],[weatherInfo objectForKey:@"city"], [weatherInfo objectForKey:@"weather1"], [weatherInfo objectForKey:@"temp1"]]);

// 从中国天气预报网请求数据  NSURL *url = [ NSURL URLWithString:@"http://www.weather.com.cn/adat/sk/101010100.html"];    // 创建请求  NSURLRequest *request = [NSURLRequest requestWithURL:url];    [[[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {        // 在网络完成的 Block 回调中,要增加错误机制.    // 失败机制处理: 错误的状态码!        // 最简单的错误处理机制:    if (data && !error) {            // JSON格式转换成字典，IOS5中自带解析类NSJSONSerialization从response中解析出数据放到字典中      id obj = [NSJSONSerialization JSONObjectWithData:data options:0 error:NULL];            NSDictionary *dict = obj[@"weatherinfo"];            NSLog(@"%@---%@", dict, dict[@"city"]);    }      }] resume];

//如果json是“单层”的，即value都是字符串、数字，可以使用objectFromJSONStringNSString *json1 = @"{/"a/":123, /"b/":/"abc/"}";NSLog(@"json1:%@",json1);NSDictionary *data1 = [json1 objectFromJSONString];NSLog(@"json1.a:%@",[data1 objectForKey:@"a"]);NSLog(@"json1.b:%@",[data1 objectForKey:@"b"]);//如果json有嵌套，即value里有array、object，如果再使用objectFromJSONString，程序可能会报错（测试结果表明：使用由网络或得到的php/json_encode生成的json时会报错，但使用NSString定义的json字符串时，解析成功），最好使用objectFromJSONStringWithParseOptions：NSString *json2 = @"{/"a/":123, /"b/":/"abc/", /"c/":[456, /"hello/"], /"d/":{/"name/":/"张三/", /"age/":/"32/"}}";NSLog(@"json2:%@", json2);NSDictionary *data2 = [json2 objectFromJSONStringWithParseOptions:JKParseOptionLooseUnicode];NSLog(@"json2.c:%@", [data2 objectForKey:@"c"]);NSLog(@"json2.d:%@", [data2 objectForKey:@"d"]);