IOS5.0開始支持JSON，所以不用第三方的解析了。

//將Foundation(NSDictionary、NSData) 轉換為JSon格式的NSData 用來發送

//+ dataWithJSONObject:options:error:

//將JSON格式的Data轉換為Foundation(NSDictionary、NSData)   用來解析

//+ JSONObjectWithData:options:error:

code:

1. 解析json成dic對象
3. -(void)fetchedData:(NSData*)responseData {//parse out the json dataNSError* error;
4. NSDictionary* json =[NSJSONSerialization
5. JSONObjectWithData:responseData //1
7. options:kNilOptions
8. error:&error];
10. NSArray* latestLoans =[json objectForKey:@"loans"]; //2
12. NSLog(@"loans: %@", latestLoans); //3
13. }
15. 把對象生成json string
16. //build an info object and convert to json
17. NSDictionary* info =[NSDictionary dictionaryWithObjectsAndKeys:[loan objectForKey:@"name"],
18. @"who",
19. [(NSDictionary*)[loan objectForKey:@"location"]
20. objectForKey:@"country"],
21. @"where",
22. [NSNumber numberWithFloat: outstandingAmount],
23. @"what",
24. nil];
26. //convert object to data
27. NSData* jsonData =[NSJSONSerialization dataWithJSONObject:info
28. options:NSJSONWritingPrettyPrinted error:&error];
30. //print out the data contents
31. jsonSummary.text =[[NSString alloc] initWithData:jsonData
32. encoding:NSUTF8StringEncoding];
34. 添加json方法至dic
35. @interfaceNSDictionary(JSONCategories)
36. +(NSDictionary*)dictionaryWithContentsOfJSONURLString:(NSString*)urlAddress;
37. -(NSData*)toJSON;
38. @end
40. @implementationNSDictionary(JSONCategories)
41. +(NSDictionary*)dictionaryWithContentsOfJSONURLString:(NSString*)urlAddress{
42. NSData* data =[NSData dataWithContentsOfURL:[NSURL URLWithString: urlAddress]];
43. __autoreleasing NSError* error =nil;
44. id result =[NSJSONSerialization JSONObjectWithData:data
45. options:kNilOptions error:&error];
46. if(error !=nil)returnnil;
47. return result;
48. }
50. -(NSData*)toJSON{
51. NSError* error =nil;
52. id result =[NSJSONSerialization dataWithJSONObject:self
53. options:kNilOptions error:&error];
54. if(error !=nil)returnnil;
55. return result;
56. }@end
58. 使用列子
59. NSDictionary* myInfo =[NSDictionary dictionaryWithContentsOfJSONURLString:@"http://www.yahoo.com/news.json"];
60. NSDictionary* information =[NSDictionary dictionaryWithObjectsAndKeys:@"orange",@"apple",@"banana",@"fig",nil];
61. NSData* json =[information toJSON];
63. 判斷是否可json化
65. BOOL isTurnableToJSON =[NSJSONSerialization isValidJSONObject: object]