IPhone - Get file last modified date from web server

Question

I want to check the last modified date on a file on a web server. Any help would be great. Thanks.

Answer 1

NSURLRequest *request = [[NSURLRequest alloc] initWithURL:aURL];
NSHTTPURLResponse *response;
[NSURLConnection sendSynchronousRequest:request                 returningResponse:&response error:nil];
if( [response respondsToSelector:@selector( allHeaderFields )] )
{
    NSDictionary *metaData = [response allHeaderFields];
    NSString *lastModifiedString = [metaData objectForKey:@"Last-Modified"];
}

Answer 2

This will first download the whole file from the server. I have modified the code myself in order to just get the header info. Here's the code

NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:urlString cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:60.0f];
[request setHTTPMethod:@"HEAD"];

NSHTTPURLResponse *response;
[NSURLConnection sendSynchronousRequest:request returningResponse:&response error:nil];

if( [response respondsToSelector:@selector( allHeaderFields )] )
{
    NSDictionary *metaData = [response allHeaderFields];
    NSString *lastModifiedString = [metaData objectForKey:@"Last-Modified"];
    NSLog(@"Date = %@",lastModifiedString);
}

[request release];

Answer 3

You can have the CMS write a file containing a date of modification. You can then download that file using a number of [:initWithURL] methods. Compare that date to the whatever stored date that you have.

I suppose you can also ftp the desired file. Then use NSFileManager to look at properties of the file, NSString *NSFileModificationDate will give you a date that you can compare with whatever stored date you want.

You can search SO for ftp solutions.