(Objective-C) Get the Last-Modified Date Before HTTP Download

Demonstrates how to send a HEAD request to get the last-modified date of a file on a web server (without downloading the file).

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#import <CkoHttp.h>
#import <CkoHttpResponse.h>
#import <NSString.h>
#import <CkoDateTime.h>
#import <CkoDtObj.h>

// This example assumes the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

CkoHttp *http = [[CkoHttp alloc] init];

CkoHttpResponse *resp = [http GetHead: @"https://www.chilkatsoft.com/hamlet.xml"];
if (http.LastMethodSuccess == NO) {
    NSLog(@"%@",http.LastErrorText);
    return;
}

// Examine the response header.
NSLog(@"%@",resp.Header);

// Here is a sample response header:

// 	Content-Length: 279658
// 	Content-Type: text/xml
// 	Last-Modified: Thu, 12 May 2016 15:14:08 GMT
// 	Accept-Ranges: bytes
// 	ETag: "c1cd8bee60acd11:0"
// 	Server: Microsoft-IIS/8.5
// 	X-Powered-By: ASP.NET
// 	X-Powered-By-Plesk: PleskWin
// 	Date: Thu, 25 Jul 2019 16:40:54 GMT

// Get the Last-Modified header.
NSString *lastModStr = [resp GetHeaderField: @"Last-Modified"];
// If the header exists...
if (resp.LastMethodSuccess == YES) {
    // Parse the RFC822 format date/time string
    CkoDateTime *ckdt = [[CkoDateTime alloc] init];
    [ckdt SetFromRfc822: lastModStr];

    // If we want to access individual date/time parts (in the local timezone)
    CkoDtObj *dt = [ckdt GetDtObj: YES];
    NSLog(@"%@%d%@%d%@%d",@"day/month/year = ",[dt.Day intValue],@"/",[dt.Month intValue],@"/",[dt.Year intValue]);

}