Serialize an Array of data

Question

I currently write to and read from an array of data, and use the index of each element to achieve something. I need a way to store this array, I looked at the user defaults, but that stores a dictionary, with retieval using keys. I will not know what key was stored.

What is the best was to store ths array of data on the iphone?

Regards

Answer 1

NSKeyedArchiver, a concrete subclass of NSCoder, provides a way to encode objects (and scalar values) into an architecture-independent format that can be stored in a file.

So you can serialize anything you like to a file:

// need a path
- (NSString*) getPath
{ 
    NSString* path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    return [path stringByAppendingPathComponent:@"someInfo"];
}

// save an array
- (void) save:(NSArray*)array
{
    [NSKeyedArchiver archiveRootObject:array toFile:[self getPath]];    
}

// get that array back
- (NSArray*) load
{
     return [NSKeyedUnarchiver unarchiveObjectWithFile:[self getPath]];       
}

You might want to serialize a dictionary of arrays if you have more than one you want to store.

Answer 2

It is possible to store an array in NSUserDefaults. It does however depend on the kind of objects the array holds. NSKeyedArchiver is another good option, as is storing the array as a plist. It could even be that CoreData is the best choice for you. It all depends on the expected size of your data and how you use it. NSKeyedArchiver seems a fair enough middle ground for many situations, but to answer you question more info is needed.