iOS 数据类型转换

1~ 字典转换成Json字符串

    NSMutableDictionary * dataDic = [[NSMutableDictionaryalloc]init];

    [dataDicsetValue:@"haha1"forKey:@"1"];

    [dataDicsetValue:@"lala2"forKey:@"2"];

    [dataDicsetValue:@"wowo3"forKey:@"3"];

    [dataDicsetValue:@"dudu4"forKey:@"4"];

   NSError *parseError =nil;

    NSData  *jsonData = [NSJSONSerialization  dataWithJSONObject:dataDic options:NSJSONWritingPrettyPrinted  error:&parseError];

//NSData转换成字符串

   NSString *strJson =  [[NSStringalloc]initWithData:jsonDataencoding:NSUTF8StringEncoding];

解析：

 NSError *error =nil;

    NSDictionary *dictionary =[NSJSONSerializationJSONObjectWithData:jsonDataoptions:kNilOptionserror:&error];

2~字符串转NSData

NSString * str = @"hahahahahahahah";

NSData * data = [strdataUsingEncoding:NSUTF8StringEncoding];