Get NSArray/NSDictionary for Nested JSON - ios

Question

I have this JSON :
{
"_id" : "class_1",
"schedule" : [
{
"date" : "1-1-2014",
"subjects" : [
{
"time_range" : "08:00-10:00",
"subject" : "Sports"
},
{
"time_range" : "10:00-12:00",
"subject" : "History"
}
]
},
{
"date" : "2-1-2014",
"subjects" : [
{
"time_range" : "08:00-10:00",
"subject" : "Physics"
},
{
"time_range" : "10:00-12:00",
"subject" : "Chemistry"
},
{
"time_range" : "10:00-12:00",
"subject" : "Biology"
}
]
},
{
"date" : "3-1-2014",
"subjects" : [
{
"time_range" : "08:00-10:00",
"subject" : "English"
},
{
"time_range" : "10:00-12:00",
"subject" : "Maths"
}
]
},
{
"date" : "4-1-2014",
"subjects" : [
{
"time_range" : "08:00-10:00",
"subject" : "Spanish"
},
{
"time_range" : "10:00-12:00",
"subject" : "Choreography"
},
{
"time_range" : "12:00-14:00",
"subject" : "Music"
},
{
"time_range" : "14:00-16:00",
"subject" : "Sports"
},
{
"time_range" : "16:30-18:30",
"subject" : "Religion"
}
]
}
]
}
What I would like to do is get an NSArray/NSMutableArray or NSDictionary/NSMutableDictionary` with the subjects for a GIVEN date. So for example if I type in the date 4-1-2014, I would like to get an array or dictionary with the 5 subjects that are contained in that date.
What I would like to do is get an NSArray/NSMutableArray or NSDictionary/NSMutableDictionary with the subjects for a GIVEN date. So for example if I type in the date 1-1-2014, I would like to get an array or dictionary with the 2 subjects that are contained in that date.
This is what I have tried:
//NSDICTIONARY CONTAINING CLASS DATA FOR CLASS ID
NSDictionary *classData =
[NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingAllowFragments error:&error];
//NSMUTABLEDICTIONARY CONTAINING SCHEDULE DATA FOR CLASS ID
NSMutableArray *scheduleDatabyClassID = [classData objectForKey:#"schedule"];
//NSMUTABLEARRAY CONTAINING SCHEDULE SUBJECTS OF CLASS ID
NSMutableArray *subjectsDatabyDate =[[NSMutableArray alloc] init] ;
for (NSMutableDictionary *subjectsData in scheduleDatabyClassID ){
NSString *subjectsData_temp = [subjectsData objectForKey:#"subjects"];
NSString *schedule_date = [subjectsData objectForKey:#"date"];
NSString *check = #"25-11-2013";
if ([schedule_date isEqualToString:check]) {
[subjectsDatabyDate addObject:subjectsData_temp];
}
}
Below is what I would like to get, but WITHOUT MANUALLY setting the index to 0. I want subjectsDataByDate : for the value (1-1-2014) for example.
NSLog(#"subjectsDatabyDate \n %# ", [subjectsDatabyDate objectAtIndex:0]);

Answer 1

This did the trick. As I mentioned, I needed a function that returns me an NSArray with containing the GIVEN date:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"date==%#",#"1-1-2014"];
NSArray *result_wanted = [scheduleDatabyClassID filteredArrayUsingPredicate:predicate];
NSLog(#"THE RESULT \n %# ", result_wanted);

Answer 2

If you do this for many different dates, and repeatedly, I would proceed somehow different.
NSDictionary is a class for key-value pairs. Your whole JSON data is actually a dictionary with keys "_id" and "schedule", and "schedule" has an array value. But looking at the data, a dictionary would have been much more appropriate, with for example "1-1-2014" as key and the rest as data. So you could turn the whole array into a dictionary, similar to your own code:
NSMutableDictionary *subjectsDatabyDate =[NSMutableDictionary dictionary] ;
for (NSDictionary *subjectsData in scheduleDatabyClassID )
{
NSString *schedule_date = [subjectsData objectForKey:#"date"];
subjectsDatabyDate [schedule_date] = subjectsData;
}
Now you can access any date very quickly:
NSDictionary* result_wanted = subjectsDatabyDate [#"1-1-2014"];
The difference is that access to an NSDictionary uses a hash table that will go directly to the item that you want, while the "filteredArray" has to iterate through the whole array, every time you look for a date.