Saving an NSArray with a Key into PList is easy. You can start with a NSMutableDictionary and add each array as an entry with a key. Finally save into file.
+(void) saveArrayIntoPlist:(NSArray*)aArray withKey:(NSString*)arrayKey {
CCLOG(@"savePhotoIdArrayToDoc");
NSString *docDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *filePath = [NSStringstringWithFormat:@"%@/info.plist", docDir];
NSMutableDictionary *info = [[NSMutableDictionary alloc] initWithContentsOfFile:filePath];
if (info != nil) {
[info setObject:aArray forKey:arrayKey];
[info writeToFile:filePath atomically:YES];
[info release];
}
else {
info = [NSDictionarydictionaryWithObject:aArray forKey:arrayKey];
[info writeToFile:filePath atomically:YES];
}