creating JSON format in Objective C

问题

For an application i want to create a JSON in format as mentioned below,

"Students" : {
    "results": {
        "Grade1": {
            "studentresult": "pass",
            "marksheet": "provided"
        },
        "ID": 01,
        "Name": "Student1", 
    }
}

I am using the following code to create the same,

NSMutableDictionary *gradedetails = [[NSMutableDictionary alloc] init];
[gradedetails setObject:@"pass" forKey:@"studentresult"];
[gradedetails setObject:@"provided" forKey:@"marksheet"];

NSMutableDictionary *sdetails = [[NSMutableDictionary alloc] init];
[sdetails setObject:@"01" forKey:@"ID"];
[sdetails setObject:@"Name" forKey:@"Student1"];

NSMutableDictionary *grade = [[NSMutableDictionary alloc] init];
[grade setObject:gradedetails forKey:@"Grade1"];

NSMutableArray *rarray = [[NSMutableArray alloc] init];
[rarray addObject:grade];
[rarray addObject:sdetails];

NSMutableDictionary *results = [[NSMutableDictionary alloc] init];
[results setObject:rarray forKey:@"results"];

NSMutableDictionary *stud = [[NSMutableDictionary alloc] init];
[stud setObject:rdic forKey:@"Students"];

NSData *jsondata = [NSJSONSerialization dataWithJSONObject:stud options:NSJSONWritingPrettyPrinted error:&error];

I am getting in the following format,

"Students" : {
"results" : [
  {
    "Grade1" : {
      "studentresult" : "pass",
      "marksheet" : "provided" 
    }
  },
  {
    "ID" : "01",
    "Name" : "Student1"
  }
]

} }

could someone please help me in creating the format.

Thanks.

回答1:

Required Data , You can get this way . Just convert that stud dict in JSon or any other format you want. Remove that array , You don't need it , As you mentioned it in the required format.

NSMutableDictionary *gradedetails = [[NSMutableDictionary alloc] init];
[gradedetails setObject:@"pass" forKey:@"studentresult"];
[gradedetails setObject:@"provided" forKey:@"marksheet"];

NSMutableDictionary *sdetails = [[NSMutableDictionary alloc] init];
[sdetails setObject:@"01" forKey:@"ID"];
[sdetails setObject:@"Name" forKey:@"Student1"];
[sdetails setObject:gradedetails forKey:@"Grade1"];

NSMutableDictionary *results = [[NSMutableDictionary alloc] init];
[results setObject:sdetails forKey:@"results"];

NSMutableDictionary *stud = [[NSMutableDictionary alloc] init];
[stud setObject:results forKey:@"Students"];

NSLog(@"Required Format Data is %@",stud);

回答2:

Depends on your code:

NSMutableDictionary *gradedetails = [[NSMutableDictionary alloc] init];
[gradedetails setObject:@"pass" forKey:@"studentresult"];
[gradedetails setObject:@"provided" forKey:@"marksheet"];

NSMutableDictionary *results = [[NSMutableDictionary alloc] init];
[results setObject:gradedetails forKey:@"Grade1"];
[results setObject:@"01" forKey:@"ID"];
[results setObject:@"Name" forKey:@"Student1"];

NSMutableDictionary *stud = [[NSMutableDictionary alloc] init];
[stud setObject:results forKey:@"Students"];

回答3:

NSDictionary *gradedetails = @{@"studentresult" : @"pass", @"marksheet" : @"provided"};
NSDictionary *grade = @{ @"Grade1" : gradedetails}
NSDictionary *sdetails = @{@"ID" : @"01", @"Student1" : @"Name"};
NSArray *resultsArray = @[grade, sdetails];
NSDictionary *results= @{@"results" : resultsArray};
NSDictionary *stud = @{@"Students" : results};

NSData *jsondata = [NSJSONSerialization dataWithJSONObject:stud options:NSJSONWritingPrettyPrinted error:&error];

I wonder why few developper use this notation

回答4:

    check this code-
  NSMutableDictionary *students=[NSJSONSerialization JSONObjectWithData:webData        options:0 error:nil];
      for (NSDictionary *dictionofstudents in students)
      {
           NSMutableDictionary *results=[dictionofstudents objectForKey:@"results"];
           for (NSDictionary *dictionofresults in results)
           {
               NSMutableDictionary *grade1=[dictionofresults objectForKey:@"Grade1"];
               for (NSDictionary *dictionofgrade1 in grade1) 
               {
                   NSString *studentresult=[dictionofgrade1 objectForKey:@"studentresult"];
                   NSString *marksheet=[dictionofgrade1 objectForKey:@"marksheet"];
                   [arrayofstudentresult addObject:studentresult];
                   [arrayofmarksheet addObject:marksheet];
               }
               NSString *ID=[dictionofresults objectForKey:@"ID"];
               NSString *name=[dictionofresults objectForKey:@"Name"];
              [arrayofID addObject:ID];
              [arrayofname addObject:name];
           }
      }

回答5:

In order to get the format you want out of it, you have to pack information in that particular format.

Your problem is right about here:

NSMutableArray *rarray = [[NSMutableArray alloc] init];
[rarray addObject:grade];
[rarray addObject:sdetails];

The desired format has no arrays, so why are you creating an array?

A hint for you:

You should be creating exactly 4 dictionaries, and no arrays.

回答6:

NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
NSMutableDictionary *result = [[NSMutableDictionary alloc] init];
NSMutableDictionary *grade = [[NSMutableDictionary alloc] init];
[grade setValue:@"pass" forKey:@"studentresult"];
[grade setValue:@"provided" forKey:@"marksheet"];
[result setValue:grade forKey:@"Grade1"];
[result setValue:@"01" forKey:@"ID"];
[result setValue:@"Student1" forKey:@"Name"];
[dict setValue:result forKey:@"results"];

NSMutableDictionary *stdnt = [[NSMutableDictionary alloc] init];
[stdnt setValue:dict forKey:@"Students"];
NSError *error = nil;
NSData *jsondata = [NSJSONSerialization dataWithJSONObject:stdnt options:NSJSONWritingPrettyPrinted error:&error];

NSString *s = [[NSString alloc] initWithData:jsondata encoding:NSUTF8StringEncoding];
NSLog(@"%@",s);

It may helps you.

来源：https://stackoverflow.com/questions/16057281/creating-json-format-in-objective-c