iPhone dev - Write/read an array of objects to a file

I've got the array called listOfContactsToLay - it contains Contact objects with 3 string fields. How can I 开发者_开发技巧write this array to file successfully? Here what I've got:

-(NSString*)fPath
{
    return [DocumentsDirectory() stringByAppendingPathComponent:@"quickdial.xml"];
}

//SERIALIZATION
- (void) save:(NSMutableArray*)array
{

   [NSKeyedArchiver archiveRootObject:array toFile:[self fPath]]; 

    NSLog(@"List of contacts been written in file");

}

// get that array back
- (NSMutableArray*)load
{
    NSLog(@"List of contacts is being read from file");
    return [NSKeyedUnarchiver unarchiveObjectWithFile:[self fPath]];

}

And of course the following doesn't work:

-(IBAction)doneWithContacts {
    [ContactManager createXmlInMydocumentsDirectory];
[self save:listOfContactsToLay];
    NSLog(@"List of contacts to lay saved!");
    [self.parentViewController dismissModalViewControllerAnimated:YES];

}

it throws invalid argument exception.

What should I do? how do I serialize the MSMutableArray of my objects? Thanks

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Whether your Contact class conforms to NSCoding protocol.

More info.

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Do you care about the format of the file? If not, why not use the built-in methods of the NSArray class?

+ (id)arrayWithContentsOfFile:(NSString *)aPath;
- (BOOL)writeToFile:(NSString *)path atomically:(BOOL)flag;

See the NSArray Class Reference.