How to create an NSDictionary with multiple keys?

问题:

I am not sure if what I am going to ask is actually an NSDictionary with multiple keys but ok.

What I want to do is create an NSDictionary with keys and values for my data and then convert it to JSON format. The JSON format would look exactly like this :

{
    "eventData": {
        "eventDate": "Jun 13, 2012 12:00:00 AM",
        "eventLocation": {
            "latitude": 43.93838383,
            "longitude": -3.46
        },
        "text": "hjhj",
        "imageData": "raw data",
        "imageFormat": "JPEG",
        "expirationTime": 1339538400000
    },
    "type": "ELDIARIOMONTANES",
    "title": "accIDENTE"
}

I ve only used NSDictionaries like this :

NSArray *keys = [NSArray arrayWithObjects:@"eventDate", @"eventLocation", @"latitude"  nil];
NSArray *objects = [NSArray arrayWithObjects:@"object1", @"object2", @"object3", nil]; 
dictionary = [NSDictionary dictionaryWithObjects:objects forKeys:keys];

But the above format is not all about key - value. So my question is how would the NSDictionary be , to fit the JSON format?? Thanks for reading my post , and sorry if any confusion.

回答1:

You know you can have a NSDictionary inside another NSDictonary right?

NSDictionary *eventLocation = [NSDictionary dictionaryWithObjectsAndKeys:@"43.93838383",@"latitude",@"-3.46",@"latitude", nil];

NSMutableDictionary *eventData = [NSDictionary dictionaryWithObjectsAndKeys:eventLocation,@"eventLocation", nil];
[eventData setObject:@"Jun 13, 2012 12:00:00 AM" forKey:@"eventDate"];
[eventData setObject:@"hjhj" forKey:@"text"];
.
.
.
NSMutableDictionary *finalDictionary = [NSMutableDictionary dictionaryWithObjectsAndKeys:eventData,@"eventData", nil];
[finalDictionary setObject:@"ELDIARIOMONTANES" forKey:@"type"];
[finalDictionary setObject:@"accIDENTE" forKey:@"title"];

回答2:

Now with Objective-C literals there is a much better, easier, and cleaner way of accomplishing this. Here is your exact dictionary with this new syntax:

NSDictionary *dictionary = @{
    @"eventData": @{
        @"eventDate": @"Jun 13, 2012 12:00:00 AM",
        @"eventLocation": @{
            @"latitude": @43.93838383,
            @"longitude": @-3.46
        },
        @"text": @"hjhj",
        @"imageData": @"raw data",
        @"imageFormat": @"JPEG",
        @"expirationTime": @1339538400000
    },
    @"type": @"ELDIARIOMONTANES",
    @"title": @"accIDENTE"
};

// Prints: "43.93838383"
NSLog(@"%@", dictionary[@"eventData"][@"eventLocation"][@"latitude"]);

回答3:

How to Create NSArray and with Access for object using NSDictionary ?

... Create NSArray

NSArray *studentkeys = [NSArray arrayWithObjects:@"studentName", @"studentBirthDate", @"studentCity", @"studentMobile"  nil];

NSArray *objects = [NSArray arrayWithObjects:@"Pravin", @"27/08/1990", @"Bhavnagar",@"7878007531", nil]; 

...to Access to NSArray Object Using NSDictionary

NSDictionary *dictionary = [NSDictionary dictionaryWithObjects:objects forKeys:keys];                                  

回答4:

Here is the structure:
Your root object is NSMutableDictionary
eventData - key for object NSMutableDictionary with keys and objects:
->key eventDate object NSString
->key eventLocation object NSMutableDictionary with keys and objects:
----> key latitude object NSNumber
----> key longitude object NSNumber
-> key text object NSString
-> key imageData object NSString later converted to NSData
-> key imageFormat object NSString
-> key expirationTime object NSNumber
type key for object NSString
title key for object NSString

回答5:

if you want multiple categories , you can follow this format

NSDictionary *jsonObject = @{
                           @"data1":@[
                              @{
                                @"title":@"A"

                                @"subData" : @[
                                @{
                                  @"title":@"aa"
                                 }]
                                }

                             ]
                         };