iOS-JSON数据与NSDictionary和NSArray之间的转化

• 1、将字典或者数组转化为JSON串

NSError *error = nil;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:theData options:NSJSONWritingPrettyPrinted error:&error];

NSString *jsonString = [[NSString alloc]initWithData:jsonData encoding:NSUTF8StringEncoding];                     

• 2、将JSON串转化为NSDictionary或NSArray
• 将NSString转化为NSData

[jsonString dataUsingEncoding:NSASCIIStringEncoding];

• 将JSON串转化为字典或者数组

id jsonObject = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingAllowFragments error:&error];