Singleton Array Won't Store Data Model - ios

Question

I'm using a singleton class (contactStorage) and a data model (contactModel) to store a list of contacts. I have created a contact object in my viewdidload of my root view controller and attempted to add it to the NSMutableArray but it will not "stick". I have logged the incoming object inside the addContact procedure and it produces accurate output, however, the addObject:c does not add it to the array. Any insight on this?
#import "contactListViewController.h"
#import "contactDetailScreenViewController.h"
#import "ContactModel.h"
#import "contactStorage.h"
#interface contactListViewController ()
#end
#implementation contactListViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
ContactModel* c = [[ContactModel alloc] initWithfName:#"Mike" andlName:#"Deasy" andEmail:#"mid31#pitt.edu" andPhone:#"4127154194"];
[c logContact];
[[contactStorage shared]addContact:c];
[[contactStorage shared]saveToFile];
[c release];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
The code for my singleton:
//
// contactStorage.m
// contactList
//
// Created by dev on 10/23/13.
// Copyright (c) 2013 Deasy, Michael William. All rights reserved.
//
#import "contactStorage.h"
#implementation contactStorage
{
}
#synthesize cList = _cList;
static contactStorage* _myOnlyInstance = nil;
#pragma mark Storage Methods
-(void)addContact: (ContactModel*) c
{
[c logContact];
[self.cList addObject:c];
NSLog(#"%#", _cList);
}
-(ContactModel*)getContact: (NSIndexPath*) index
{
return [self.cList objectAtIndex:index.row];
}
-(NSMutableArray*)deleteContact: (NSIndexPath*) index
{
[self.cList removeObjectAtIndex:index.row];
return self.cList;
}
-(NSMutableArray*)getAllContacts
{
return self.cList;
}
-(void)saveToFile
{
NSString* path = [[self documentsPath] stringByAppendingPathComponent:#"data.txt"];
NSLog(#"%#",path);
[_cList writeToFile:path atomically:YES];
NSLog(#"%#", self.cList);
}
#pragma mark Singleton Create
-(id)init
{
self = [super init];
if (self)
{
NSLog(#"Initing the array");
_cList = [[NSMutableArray alloc] init];
}
return self;
}
+(contactStorage*)shared
{
if (_myOnlyInstance == nil)
{
_myOnlyInstance = [[contactStorage alloc] init];
}
return _myOnlyInstance;
}
-(NSString*) documentsPath
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDir = [paths objectAtIndex:0];
return documentsDir;
}
#end
The code for my contactModel:
//
// ContactModel.m
// contactList
//
// Created by dev on 10/23/13.
// Copyright (c) 2013 Deasy, Michael William. All rights reserved.
//
#import "ContactModel.h"
#implementation ContactModel
{
}
#synthesize fName = _fName;
#synthesize lName = _lName;
#synthesize email = _email;
#synthesize phone = _phone;
-(void)logContact
{
NSLog(#"%#", self.fName);
NSLog(#"%#", self.lName);
NSLog(#"%#", self.email);
NSLog(#"%#", self.phone);
}
-(void)dealloc
{
[_fName release];
[_lName release];
[_email release];
[_phone release];
[super dealloc];
}
-(id) initWithfName: (NSString*) fName
andlName: (NSString*) lName
andEmail: (NSString*) email
andPhone: (NSString*) phone
{
self = [super init];
_fName = [[NSString alloc] initWithString:fName];
_lName = [[NSString alloc] initWithString:lName];
_email = [[NSString alloc] initWithString:email];
_phone = [[NSString alloc] initWithString:phone];
return self;
}
#end
NSLog Output:
2013-10-24 12:50:35.573 contactList[3097:a0b] Mike
2013-10-24 12:50:35.574 contactList[3097:a0b] Deasy
2013-10-24 12:50:35.575 contactList[3097:a0b] mid31#pitt.edu
2013-10-24 12:50:35.575 contactList[3097:a0b] 4127154194
2013-10-24 12:50:35.576 contactList[3097:a0b] Initing the array
2013-10-24 12:50:35.576 contactList[3097:a0b] Mike
2013-10-24 12:50:35.576 contactList[3097:a0b] Deasy
2013-10-24 12:50:35.577 contactList[3097:a0b] mid31#pitt.edu
2013-10-24 12:50:35.577 contactList[3097:a0b] 4127154194
2013-10-24 12:50:35.578 contactList[3097:a0b] (
"<ContactModel: 0x8d72720>"
)
2013-10-24 12:50:35.578 contactList[3097:a0b] /Users/dev/Library/Application Support/iPhone Simulator/7.0/Applications/7CFD98F0-C502-49E5-953B-FD43B61EDC38/Documents/data.txt
2013-10-24 12:50:35.579 contactList[3097:a0b] (
"<ContactModel: 0x8d72720>"
)

Answer 1

Clearly, your singleton is successfully adding the ContactModel object to the array of your singleton (as evidenced by your NSLog statement). I assume your question stems from the fact that you're not seeing your file saved.
That's because you're trying to use writeToFile of your NSMutableArray (which tries to save a plist file). If you check the return code of writeToFile, you'll see it failed. This is because you cannot write a plist with an array consisting of custom objects. You might want to use NSKeyedArchiver instead, e.g.:
- (void)saveToFile
{
NSString* path = [[self documentsPath] stringByAppendingPathComponent:#"cList.dat"];
BOOL success = [NSKeyedArchiver archiveRootObject:_cList toFile:path];
NSAssert(success, #"write failed");
}
Anticipating the logical follow-up question, how to read the file, you would use NSKeyedUnarchiver, like so:
-(void)loadFromFile
{
NSString* path = [[self documentsPath] stringByAppendingPathComponent:#"cList.dat"];
self.cList = [NSKeyedUnarchiver unarchiveObjectWithFile:path];
NSAssert(_cList, #"read failed");
}
But, for this to work, you have to make your contact model conform to the NSCoding protocol, namely adding the following methods to that class:
#pragma mark - NSCoding methods
- (NSArray *)propertyNames
{
return #[#"fName", #"lName", #"email", #"phone"];
}
- (id) initWithCoder:(NSCoder *)aDecoder
{
// if `super` conforms to `NSCoding`, then use
//
// self = [super initWithCoder:aDecoder];
//
// in this case, `super` is `NSObject`, so just call `init`
self = [super init];
if (self) {
for (NSString *key in [self propertyNames]) {
[self setValue:[aDecoder decodeObjectForKey:key] forKey:key];
}
}
return self;
}
- (void)encodeWithCoder:(NSCoder *)aCoder
{
// if `super` conforms to `NSCoding`, itself, then call `encodeWithCoder` for `super`:
//
// [super encodeWithCoder:aCoder];
//
// in this case, `super` is `NSObject`, so that is not needed
for (NSString *key in [self propertyNames]) {
[aCoder encodeObject:[self valueForKey:key] forKey:key];
}
}
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