Objective-C

Set a Custom Last-Modified Date in a Gzip File

See more Gzip Examples

This example demonstrates how to use the SetDt method to specify a custom last-modified date and time that will be embedded in a Gzip file.

A CkDateTime object is first initialized with a specific date/time using an RFC 822 formatted string. This date/time is then applied to the Gzip object using SetDt.

When a compression method is called (such as CompressStringToFile), the specified date/time is included in the Gzip metadata. This allows the resulting .gz file to carry a meaningful timestamp rather than using the current system time.

Objective-C

#import <CkoGzip.h>
#import <CkoDateTime.h>
#import <NSString.h>

BOOL success = NO;

// This example demonstrates how to set a custom last-modified date/time
// that will be embedded in a Gzip file.

CkoGzip *gzip = [[CkoGzip alloc] init];
CkoDateTime *dt = [[CkoDateTime alloc] init];

// Set the date/time using a timestamp format (ISO 8601 style):
[dt SetFromTimestamp: @"2025-11-15T12:45:26-05:00"];

// Apply the date/time to the Gzip object:
success = [gzip SetDt: dt];
if (success == NO) {
    NSLog(@"%@",gzip.LastErrorText);
    return;
}

// Compress a string so the custom date/time is embedded in the .gz:
NSString *inputStr = @"Example text for Gzip compression.";
success = [gzip CompressStringToFile: inputStr destCharset: @"utf-8" destPath: @"output.gz"];
if (success == NO) {
    NSLog(@"%@",gzip.LastErrorText);
    return;
}

NSLog(@"%@",@"Gzip file created with custom last-modified date.");