How to access a json file locally from within the app - iphone

Question

I'm trying to figure out how to access a json file locally, from within the app. Currently I've been using the json file remotely from a server like this:
jsonStringCategory = #"http://****categories?country=us";
}
// Download the JSON file
NSString *jsonString = [NSString
stringWithContentsOfURL:[NSURL URLWithString:jsonStringCategory]
encoding:NSStringEncodingConversionAllowLossy|NSUTF8StringEncoding
error:nil];
NSLog(#"jsonStringCategory is %#", jsonStringCategory);
NSMutableArray *itemsTMP = [[NSMutableArray alloc] init];
// Create parser
SBJSON *parser = [[SBJSON alloc] init];
NSDictionary *results = [parser objectWithString:jsonString error:nil];
itemsTMP = [results objectForKey:#"results"];
self.arForTable = [itemsTMP copy];
[self.tableView reloadData];
I tried this:
NSString *filePath = [[NSBundle mainBundle] pathForResource:#"categoriesus" ofType:#"json"];
jsonStringCategory = [[NSString alloc] initWithContentsOfFile:filePath];
thanks

Answer 1

NSString *filePath = [[NSBundle mainBundle] pathForResource:#"filename" ofType:#"json"];
NSData *jsonData = [NSData dataWithContentsOfFile:filePath];
NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:jsonData options:kNilOptions error:nil];

Answer 2

Could you be more specific? which file do you try to access? did you already save it?
1/ For your main problem: you can create a dictionnary or array with a file path
[NSDictionary dictionaryWithContentsOfFile:<#(NSString *)#>]
[NSArray arrayWithContentsOfFile:<#(NSString *)#>]
2/ But you can, as you wrote it, read the "string" content from a file and then, eventually, parse it. For that you need (for example) a path like this (for the "directory" dir, could be the "cache" dir)
NSArray *array = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *pathToFile = [ [ [ [ array objectAtIndex:0 ] stringByAppendingPathComponent:#"nameOfTheFile" ] stringByAppendingString:#".ext" ] retain ];
And then use "pathToFile" in my 1/ example.
3/ For your internet access, I recommend you to check AFNetworking. It's better to do async download ;-) (yours is synchronous)
https://github.com/AFNetworking/AFNetworking

Answer 3

I like to use CoreData. Follow those steps:
1-)First of all create a model, and add attribute String type with name jsonvalue.
2-)create this function to save your json file:
-(void)saveJson:(NSString*)d
{
NSString * data = [d retain];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:[NSEntityDescription entityForName:#"NameObjectModel" inManagedObjectContext:context]];
NSError *error = nil;
NSArray *results = [context executeFetchRequest:request error:&error];
[request release];
// error handling code
if(error){
}
else{
Session* favoritsGrabbed = [results objectAtIndex:0];
favoritsGrabbed.jsonvalue = data;
}
if(![context save:&error]){
NSLog(#"data saved.");
}
}
3-)create a function to load your json:
-(void)loadJSONFromFile
{
//Recover data from core data.
// Define our table/entity to use
NSEntityDescription *entity = [NSEntityDescription entityForName:#"NameObjectModel" inManagedObjectContext:context];
// Setup the fetch request
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:entity];
// Define how we will sort the records - atributo que sera recuperado
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"jsonvalue" ascending:NO];
NSArray *sortDescriptors = [NSArray arrayWithObjects:sortDescriptor, nil];
[request setSortDescriptors:sortDescriptors];
[sortDescriptor release];
// Fetch the records and handle an error
NSError *error;
NSMutableArray *mutableFetchResults = [[NSMutableArray alloc]initWithArray:[context executeFetchRequest:request error:&error]];
if (!mutableFetchResults) {
// Handle the error.
// This is a serious error and should advise the user to restart the application
}
if(mutableFetchResults.count == 0)
{
NSLog(#"the archive is null");
}
else if(mutableFetchResults.count > 0)
{
NameObjectModel *entity = [mutableFetchResults objectAtIndex:0];
//NSLog(#"%#",[[entity jsonvalue] JSONValue]);
NSDictionary * aux = [[entity jsonvalue] JSONValue];
if([entity jsonvalue]== nil)
{
NSLog(#"json is nil");
NSLog(#"the archive exists but json is nil");
}
else {
// set current json data cache
[self setJsonCache:aux]; // add to recovery list
}
}
[mutableFetchResults release];
[request release];
}
Don't forget: NameObjectModel = Name of your NSManagedObject.