Can't retrieve data after storing to disk using NSKeyedArchiver - objective-c

Question

I'm storing a custom object in a dictionary which i'm then saving to disk using NSKeyedArchiver. In the same method where I save the data, I do a quick test at the end to make sure I can load the data but everything comes out null. Why is this happening? I've been following the instructions in this tutorial: http://cocoadevcentral.com/articles/000084.php
/** Interface of viewcontroller**/
#import "User.h"
#interface BWViewController : UIViewController
{
IBOutlet UITextField *userNameField;
IBOutlet UITextField *passwordField;
IBOutlet UILabel * loginStatus;
}
#property (nonatomic, copy) NSString *holdPassword, *holdUserName;
-(IBAction)signUpButton;
-(IBAction)loginButton;
-(NSString*) pathForDataFile;
-(void) saveDataToDisk:(User*) someUser;
-(User *) loadDataFromDisk:(NSString*) theKey;
#end
/**Implementation file **/
#import "BWViewController.h"
#interface BWViewController ()
#end
#implementation BWViewController
#synthesize holdPassword,holdUserName;
-(IBAction)signUpButton
{
User * firstUser = [[User alloc] init];
firstUser.userName = userNameField.text;
firstUser.password = passwordField.text;
/**To save to file**/
[self saveDataToDisk:firstUser];
loginStatus.text = #"Thanks for signing up";
}
-(NSString*) pathForDataFile
{
NSFileManager * fileManager = [NSFileManager defaultManager];
NSString *folder =#"~/Library/Application Support/signUpApp/";
folder = [folder stringByExpandingTildeInPath];
if([fileManager fileExistsAtPath:folder] == NO)
{
[fileManager createFileAtPath:folder contents:nil attributes:nil];
}
NSString *fileName = #"signUpApp.demo";
return [folder stringByAppendingPathComponent:fileName];
}
-(void) saveDataToDisk:(User*) someUser
{
User * savingUser = someUser;
NSString * path = [self pathForDataFile];
NSMutableDictionary * rootObject = [NSMutableDictionary dictionary];
[rootObject setValue:savingUser forKey:userNameField.text];
[NSKeyedArchiver archiveRootObject:rootObject toFile:path];
NSLog(#"saving user to disk %#", savingUser.userName);
/**Testing the load process**/
User * testLoadUser;
NSMutableDictionary *unRootObject;
unRootObject = [NSKeyedUnarchiver unarchiveObjectWithFile:path];
testLoadUser = [unRootObject valueForKey:userNameField.text];
NSLog(#"Testing the unarchive %# and %#", testLoadUser.userName, testLoadUser.password);
}
/**User implementation file**/
#import "User.h"
#implementation User
#synthesize userName, password;
- (void) encodeWithCoder: (NSCoder *)coder
{
[coder encodeObject: userName forKey:#"username"];
[coder encodeObject: password forKey:#"password"];
}
- (id) initWithCoder: (NSCoder *)coder
{
if (self = [super init])
{
self.userName = [coder decodeObjectForKey:#"username"];
self.password = [coder decodeObjectForKey:#"password"];
}
return self;
}
#end

Answer 1

This looks like iOS code, but you're using a Mac OS X convention for determining the folder for the path. In iOS, you should use the Documents folder.
For iOS, the path for the filename in the Documents folder should be:
- (NSString*) pathForDataFile
{
NSString *documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
NSString *path = [documentsPath stringByAppendingString:#"signUpApp.demo"];
return path;
}
I'd also suggest checking the return code from archiveRootObject method, to confirm whether the archive succeeded or not. No point in going further if that failed.
Also, in your old pathForDataFile, you're calling createFileAtPath:contents:attributes:, but I suspect you intended createDirectoryAtURL:withIntermediateDirectories:attributes:error:. The former is for creating a file, and the latter is for creating a folder. And your code is trying to create a folder.

Answer 2

Quick things you can check..
1) IS file is Actually created on the location ?
2) Is there any data (random chars) in that file ?
3) Is your code contains <NSCopying> protocol in your user.h class?
4) Make sure you don't have - (id) initWithCoder: (NSCoder *)coder and - (void) encodeWithCoder: (NSCoder *)coder in your header file.