Question

I am currently working on having a file update from a remote server. I am able to download the file and save it to the documents directory. The file has a “Last-Modified” tag and I am using it to check if the file needs to be updated. But my question is, how do you save the string with the tag for later use? Later I want to compare the saved string with the another string with the current “Last-Modified” tag. If they are equal the file doesn’t have to be updated but if they’re not equal I will download the new file.

Sorry for bad English, correct me and any help is appreciated. Have been struggling with this for a while!

EDIT:

NSDictionary *metaData = [test allHeaderFields];

//NSLog(@"%@", [metaData description]);

lastModifiedString = [metaData objectForKey:@"Last-Modified"];

NSUserDefaults *standardUserDefaults = [NSUserDefaults standardUserDefaults];
[standardUserDefaults setObject:lastModifiedString forKey:@"LastModified"];
[standardUserDefaults synchronize];

NSString *savedString = [[NSUserDefaults standardUserDefaults] stringForKey:@"LastModified"];

if (![lastModifiedString isEqualToString:savedString])
{
    [self downloadNewFile];
}

Download link to files: Archive.zip

Answer 1

Use NSUserDefaults or Core Data to persist a value.

EDIT:

It is not working because you are saving the new value before retrieving it. You’ll need to move

NSString *savedString = [[NSUserDefaults standardUserDefaults] stringForKey:@"LastModified"];

above

[standardUserDefaults setObject:lastModifiedString forKey:@"LastModified"];

Now you’ll be comparing the new file value against the old user defaults value.