iOS comparing NSDictionary values - ios

Question

I'm fetching two JSONs and store them individually as NSArray and NSDictionary.
This is what the JSON data structures looks like
(
{
Cells = (
{
ValueName = "name";
Text = "John Appleseed";
},
{
"Option": {
"Text": "19"
},
ValueName = "age"
}, etc...
)
},
{
Cells = (
{
ValueName = "name";
Text = "John Appleseed";
},
{
ValueName = "age",
"Option": {
"Text": "19"
}
}, etc...
)
}
)
{
"map": {
"first": "name",
"second": "age"
}, etc...
}
The two has values that needs to be cross referenced (as one contains all data (allData), and the other contains a "map" (mapData) of what data is needed).
How may I compare all the values of allData with all the values of mapData while, if possible, keeping simplicity and memory in mind?
A great approach would be to use containsObject matching [allData allValues] with [mapData allValues] and being given back an NSArray with the object of the match. Alas, this is not the case. The approach perfectly illustrates what I wish to accomplish.
My initial approach is slow, memory hogging and ugly (wrote this from memory):
NSArray *allData = [NSJSONSerialization JSONObjectWithData:allDataJSON options:kNilOptions error:&JSONSerializationError];
NSDictionary *mapData = [NSJSONSerialization JSONObjectWithData:mapDataJSON options:kNilOptions error:&JSONSerializationError];
NSMutableDictionary *resultData = [[NSMutableDictionary alloc] init];
for (int count = 0; count<allData.count; count++) {
id dataValue = [allData objectAtIndex:count];
for (id key in mapData) {
if ([[mapData objectForKey:key] containsObject:dataValue]) {
[resultData setObject:[dataValue objectForKey:#"value"] forKey:key]
}
}
}
It's also important to be able to reference to each match of the values that match (as done in my approach).
This is not an opinion based question as optimisation and memory usage is not an opinion.

Answer 1

I found that using this data model is memory efficient and pretty fast (clocked in at an average time of 0.001 sec with allData's length of 1000 lines).
By extracting all wanted values from mapData and placing them in an NSArray the values can easily be matched with the values of allData.
When looping thru the mapDataArray a secondary loop can be created for going thru allData's values. If mapDataArray containsObject returns true, the data can be stored in a momentary storage dictionary.
This allows for easy management of what data is needed and what can be ignored. It is important that the momentary storage is created inside of the first loop (as you'll see in a moment).
If and when all the values from the mapDataArray is found (by checking mapDataArray.count with momentaryData.count) we can break the current loop (thus saving time and memory).
It's probably easier to just look at the code to understand what is really going on.
The data objects as referenced in the question.
NSArray *allData = [NSJSONSerialization JSONObjectWithData:allDataJSON options:kNilOptions error:&JSONSerializationError];
NSDictionary *mapData = [NSJSONSerialization JSONObjectWithData:mapDataJSON options:kNilOptions error:&JSONSerializationError];
‏
Creating the mapDataArray, looping thru it, creating the momentary dictionary, appending found objects and appending the momentary data to resultData.
NSArray *mapDataArray = [[NSArray alloc] init];
mapDataArray = [[mapDataArray arrayByAddingObjectsFromArray:[[mapData objectForKey:#"map"] objectForKey:#"first"]] arrayByAddingObjectsFromArray:[[mapData objectForKey:#"map"] objectForKey:#"second"]];
mapDataArray = [[NSOrderedSet orderedSetWithArray:mapDataArray] array]; //Remove duplicates
NSMutableDictionary *resultData = [[NSMutableDictionary alloc] init];
for (int count = 0; count<allData.count; count++) {
NSMutableDictionary *momentaryData = [[NSMutableDictionary alloc] init];
int dataNumber = count;
NSArray *literal = [[allData objectAtIndex:dataNumber] objectForKey:#"Cells"];
for (int count = 0; count<literal.count; count++) {
id literal = [[[allData objectAtIndex:dataNumber] objectForKey:#"Cells"] objectAtIndex:count];
if ([mapDataArray containsObject:[literal objectForKey:#"ValueName"]]) {
id value = [literal objectForKey:#"Text"];
if (!value) {
value = [literal objectForKey:#"Option"];
if (value && ![value isEqual:[NSNull null]]) {
value = [value objectForKey:#"Text"];
} else {
value = #"";
}
}
[momentaryData setObject:[NSString stringWithFormat:#"%#", value] forKey:[literal objectForKey:#"ValueName"]];
if (mapDataArray.count == momentaryData.count) {
break; //We have what we came for...
}
}
}
[resultData setObject:momentaryData forKey:[NSString stringWithFormat:#"%d", dataNumber]];
}

Answer 2

You can compare arrays or dictionaries using isEqual:.
For arrays it compares whether the arrays have the same number of elements or if the matching elements are equal.
For dictionaries it checks if both have the same number of keys, if set of keys is equal and if each key in one dictionary has the same value as the matching key in the other dictionary.