iOS JSON解析之NSJSONSerialization

1、概念

JSON是一种轻量级的数据格式，用于数据交互服务器返回给客户端的数据。NSJSONSerialization是苹果原生的json解析方式，使用这个类可以将JSON转化为Foundation对象，也可将Foundatio对象转化为JSON。

2、使用NSJSONSerialization进行JSON解析的前提

An object that may be converted to JSON must have the following properties:

（1）顶层对象必须是NSArray或NSDictionary

  (2) 所有对象必须是NSString,NSNumber,NSArray,NSDictionary or NULL

  (3)所有字典的键值都是字符串类型的

（4）数值不能是非数值或无穷大

3、NSJSONReadingOptions参数的含义

typedef enum NSJSONReadingOptions : NSUInteger {

NSJSONReadingMutableContainers = (1UL << 0),//被创建的数字或字典是可变的

NSJSONReadingMutableLeaves = (1UL << 1),//Json对象中创建的字符串是NSMutableString

NSJSONReadingAllowFragments = (1UL << 2)//允许顶层对象不是NSArrayh

} NSJSONReadingOptions;

4、JSON 转化为 Foundation Object

-(NSDictionary *)objectConvertByJsonStr:(NSString *)jsonStr

{

NSData *data = [jsonStr dataUsingEncoding:NSUTF8StringEncoding];

NSError *error;

NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&error];

if (error) {

NSLog(@"error:%@",error);

}

return dict;

}

5、Foundation object 转化为 Json

-(NSString *)jsonStrConvertByObject:(NSDictionary *)dict

{

//whether a given object can be converted to JSON data.

if ([NSJSONSerialization isValidJSONObject:dict]) {

NSError *error;

NSData *data = [NSJSONSerialization dataWithJSONObject:dict options:NSJSONWritingPrettyPrinted error:&error];

NSString *resultStr = [[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];

return resultStr;

}else{

return nil;

}

}