#import <UIKit/UIKit.h> 
@interface ViewController : UIViewController 
@property (retain, nonatomic) IBOutlet UITextView *txtView; 
- (IBAction)btnPressTouchJson:(id)sender; 
- (IBAction)btnPressSBJson:(id)sender; 
- (IBAction)btnPressIOS5Json:(id)sender; 
- (IBAction)btnPressJsonKit:(id)sender; 
@end 

//使用TouchJson来解析北京的天气 
- (IBAction)btnPressTouchJson:(id)sender { 
//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 
txtView.text = [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解析南阳的天气 
- (IBAction)btnPressSBJson:(id)sender { 
NSURL *url = [NSURL URLWithString:@"http://m.weather.com.cn/data/101180701.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"]; 
txtView.text = [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"]]; 
} 

- (IBAction)btnPressIOS5Json:(id)sender { 
NSError *error; 
//加载一个NSURL对象 
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://m.weather.com.cn/data/101180601.html"]]; 
//将请求的url数据放到NSData对象中 
NSData *response = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil]; 
//IOS5自带解析类NSJSONSerialization从response中解析出数据放到字典中 
NSDictionary *weatherDic = [NSJSONSerialization JSONObjectWithData:response options:NSJSONReadingMutableLeaves error:&error]; 
NSDictionary *weatherInfo = [weatherDic objectForKey:@"weatherinfo"]; 
txtView.text = [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"]]; 
NSLog(@"weatherInfo字典里面的内容为--》%@", weatherDic ); 
} 

- (IBAction)btnPressJsonKit:(id)sender { 
//如果json是“单层”的，即value都是字符串、数字，可以使用objectFromJSONString 
NSString *json1 = @"{\"a\":123, \"b\":\"abc\"}"; 
NSLog(@"json1:%@",json1); 
NSDictionary *data1 = [json1 objectFromJSONString]; 
NSLog(@"json1.a:%@",[data1 objectForKey:@"a"]); 
NSLog(@"json1.b:%@",[data1 objectForKey:@"b"]); 
[json1 release]; 
//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"]); 
[json2 release]; 
} 

- [SBJSON (json-framework)](http://code.google.com/p/json-framework/)
- [TouchJSON (from touchcode)](http://code.google.com/p/touchcode/)
- [YAJL (objective-C bindings)](http://github.com/gabriel/yajl-objc)
- [JSONKit](https://github.com/johnezang/JSONKit)
- [NextiveJson](https://github.com/nextive/NextiveJson) 
-[NSJSONSerialization](http://developer.apple.com/library/ios/#documentation/Foundation/Reference/NSJSONSerialization_Class/Reference/Reference.html#//apple_ref/doc/uid/TP40010946)