create a dictionary with an array of dictionaries - objective-c

Question

Noob here. I recently started working with objective C, and currently I am stuck with dictionary concept. I want to create a json object as shown below:
{"UserData": {
"Name": Mike Smith,
"Age": 32,
"category": [1,2,3],
"Weekly Data": [
{"Monday" : [1.0,2.0,3.0]},
{"Tuesday": [1.0,2.0,3.0]}
]
}
}
I wrote the following piece of code which doesn't give the desired result. I wonder if someone could help me.
-(NSString*)populateUserPreferences
{
NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
NSMutableArray *categorydata = [[NSMutableArray alloc] init];
NSMutableArray *weeklydata = [[NSMutableArray alloc] init];
for (int i=0;i<4; i++)
{
[categorydata addObject:[NSNumber numberWithInt:i]];
}
NSMutableArray *mondaydata = [[NSMutableArray alloc] init];
for (int j=0; j<3; j++)
{
[mondaydata addObject:[NSNumber numberWithInt:j]];
}
NSMutableArray *tuesdaydata = [[NSMutableArray alloc] init];
for (int j=0; j<3; j++)
{
[tuesdaydata addObject:[NSNumber numberWithInt:j]];
}
NSDictionary *monday = [NSDictionary dictionaryWithObject:mondaydata];
NSDictionary *tuesday = [NSDictionary dictionaryWithObject:tuesdaydata];
[weeklydata addObject: monday ];
[weeklydata addObject: tuesday ];
}
[dict setObject:[NSString stringWithFormat:"Mike Smith"] forKey:#"Name"];
[dict setObject:[NSNumber numberWithInteger:32.0] forKey:#"Age"];
[dict setObject:categorydata forKey:#"category"];
[dict setObject:weeklydata forKey:#"Weekly Data"];
NSString * userdata = [dict JSONRepresentation];
NSLog(request);
NSDictionary *userdataJson = [NSDictionary dictionaryWithObject:dict forKey:#"userData"];
return [userdataJson JSONRepresentation];
}
Thanks in advance for looking into it.
Apoorva

Answer 1

The mistake is when creating the monday and tuesday dictionary.
// mondaydata & tuesday is just array.
NSDictionary *monday = [NSDictionary dictionaryWithObject:mondaydata];
NSDictionary *tuesday = [NSDictionary dictionaryWithObject:tuesdaydata];
This code is mistake since you did not assign the dictionary properly (where is the key for the dictionary?). Instead you should do:
NSDictionary *mondayDict = [[NSDictionary alloc] init];
[mondayDict setObject:mondaydata forKey:"Monday"];
NSDictionary *tuesdayDict = [[NSDictionary alloc] init];
[tuesdayDict setObject:tuesdaydata forKey:"Tuesday"];
Then you can add mondayDict and tuesdayDict to your array weeklydata.
ps. just a note, name your variable meaningfully. For example, mondaydata is not descriptive enough. You should use mondayArr for example. To easily identify it is an array. Just a normal coding practice to share.

Answer 2

NSDictionary * dict = #{#"UserData": #{
#"Name": #"Mike Smith",
#"Age": #32,
#"category": #[#1,#2,#3],
#"Weekly Data": #[
#{#"Monday" : #[#1.0,#2.0,#3.0]},
#{#"Tuesday": #[#1.0,#2.0,#3.0]}
]
}
};
NSError * error = nil;
NSData * data = [NSJSONSerialization dataWithJSONObject:dict options:NSJSONWritingPrettyPrinted error:&error];
if (error) {
NSLog(#"%#", [error localizedDescription]);
} else {
// Do what you want
}