How to keep a variable in memory until the app quits - ios

Question

I have a singleton object in iOS that when instantiated parses a CSV file and then holds the results. I would like to make this object universally accessible and I would like it to not be released from memory until the app quits. I am running ARC so I cannot do manual retains.
Is there a way I can do this so it will work with ARC?
Header File:
#import <Foundation/Foundation.h>
#import "CHCSV.h"
#import "RCParserObject.h"
#interface ParserStore : NSObject <CHCSVParserDelegate>
{
// CSV Variables
RCParserObject *item;
NSMutableArray *data;
NSMutableArray *parsedData;
int fields;
bool open;
}
#property (atomic, retain) RCParserObject *item;
#property (atomic, retain) NSMutableArray *data;
#property (atomic, retain) NSMutableArray *parsedData;
#property (atomic) int fields;
#property (atomic) bool open;
+ (ParserStore *) defaultStore;
- (void) parseCSVFile:(NSString*)file;
- (void) categorizeData;
Implementation File
#import "ParserStore.h"
#import "RCParserObject.h"
#import "RCDetailItem.h"
static ParserStore *defaultStore;
#implementation ParserStore
#synthesize item, data, parsedData, fields, open;
# pragma mark -
# pragma mark Singleton Methods
+ (ParserStore *) defaultStore
{
if (!defaultStore)
{
defaultStore = [[super allocWithZone:NULL] init];
}
return defaultStore;
}
+ (id) allocWithZone:(NSZone *)zone
{
return [self defaultStore];
}
- (id) init
{
NSLog(#"Running init on parser store");
if (defaultStore)
{
NSLog(#"Self data count is %d, right before return", self.parsedData.count);
return defaultStore;
}
// NSLog(#"This better only happen once");
self = [super init];
[self setParsedData:[[NSMutableArray alloc] init]];
[self parseCSVFile:#"ContentNoPathFileExt2ASCII"];
[self categorizeData];
// NSLog(#"Self data count is %d when first created", self.parsedData.count);
return self;
}
#property (atomic, retain) RCParserObject *item;
#property (atomic, retain) NSMutableArray *data;
#property (atomic, retain) NSMutableArray *parsedData;
#property (atomic) int fields;
#property (atomic) bool open;
+ (ParserStore *) defaultStore;
- (void) parseCSVFile:(NSString*)file;
- (void) categorizeData;
#end

Answer 1

+(MySingleton *)singleton {
static dispatch_once_t pred;
static MySingleton *shared = nil;
dispatch_once(&pred, ^{
shared = [[MySingleton alloc] init];
shared.someVar = someValue; // if you want to initialize an ivar
});
return shared;
}
From anywhere:
NSLog(#"%#",[MySingleton singleton].someVar);
Note that your iOS app already has a singleton that you can access anywhere:
AppDelegate *delegate = (AppDelegate*)[[UIApplication sharedApplication] delegate];

Answer 2

a simple singleton would be something like... in the .h:
#interface Foo : NSObject
+ (Foo *)sharedInstance;
#end
and in the .m:
static Foo *_foo = nil;
#implementation Foo
+ (Foo *)sharedInstance {
if (!_foo)
_foo = [[Foo alloc] init];
return _foo;
}
#end