CODEWITHSUNDEEP
iphonenskeyedarchiver
tranvutuan
tranvutuan

Reputation: 6109

read and write using NSKeyedArchiver, ios

Below is a class to read and write data using nsarchive

Data.m

-(id)init {
    self        =   [super init];
    if(self) {
        arr     =   [[NSMutableArray alloc] init];
    }
    return self;
}

-(NSString *)getPath {
    NSArray     *paths          =   NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString    *documentPath;

    if ([paths count] > 0)
        documentPath            =   [paths objectAtIndex:0];

    NSString *draftDataPath     =   [documentPath stringByAppendingPathComponent:@"draftData.dat"];
    return draftDataPath;
}

-(void)saveDataToDisk {
    NSString *path              =   [self getPath];
    [NSKeyedArchiver archiveRootObject:arr toFile:path];

}

-(void)loadDataFromDisk {
    NSString    *path           =   [self getPath];
    self.arr                    =   [NSKeyedUnarchiver unarchiveObjectWithFile:path];
}

At later on, I am adding some objects into arr by doing CustomerClass.m

- (void) viewDidLoad {

Data *data = [[Data alloc] init];
[data.arr addObject:myObject1]
[data.arr addObject:myObject2]
[data.arr addObject:myObject3]
[data saveDataToDisk];
}

At DisplayData.m, I want to check data.arr by

- (void) viewDidLoad {
   Data *data = [[Data alloc] init];
   [data loadDataFromDisk];

   NSLog(@"length of array is %d",[data.arr count]);

}

On the console, I am getting

length of array is 1

I thought it should be 3 after all.

Please point out what I have just made a mistake in the middle of work if you have any clues about it.

Upvotes: 1

Views: 3640

Answers (2)

David Hoerl
David Hoerl

Reputation: 41642

So, I suspect that your "myObjects" are not NSCoding compliant. I just did this:

NSMutableArray *arr = [NSMutableArray arrayWithCapacity:3];
[arr addObject:@"Hello"];
[arr addObject:@" "];
[arr addObject:@"World"];
BOOL ret = [NSKeyedArchiver archiveRootObject:arr toFile:[self getPath]];

NSArray *arr2 = [NSKeyedUnarchiver unarchiveObjectWithFile:[self getPath]];
NSLog(@"count = %d", [arr2 count]);

And the results was "count = 3"

Upvotes: 5

Eric
Eric

Reputation: 4061

I feel like there's too much code here to do what you're looking for. I think all you need is:

[[NSUserDefaults standardUserDefaults] setObject:[NSKeyedArchiver archivedDataWithRootObject:dataClass] forKey:NSUserDefaultString];
[[NSUserDefaults standardUserDefaults] synchronize];

to save it.

And:

NSData *someData = [[NSUserDefaults standardUserDefaults] objectForKey:NSUserDefaultString];
if (settingsData != nil)
{
    dataClass = [NSKeyedUnarchiver unarchiveObjectWithData:settingsData];
}

to retrieve it.

Upvotes: 3

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