Objective-C

Compress a File to Gzip with Custom Metadata

See more Gzip Examples

This example demonstrates how to use the CompressFile method to create a Gzip (.gz) file while customizing the metadata embedded in the Gzip header.

Before compression, several properties are set:

• Comment: Adds a descriptive comment to the Gzip file.
• Filename: Specifies the filename to embed in the Gzip data, which may be used by extraction tools as the default output name.
• CompressionLevel: Controls the tradeoff between compression ratio and speed (set to maximum in this example).
• LastModStr: Sets the last-modified timestamp using an RFC 822 formatted date string.

After setting these properties, the input file is compressed and written to a .gz file. This approach allows you to embed meaningful metadata along with the compressed data.

Objective-C

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

BOOL success = NO;

//  This example demonstrates how to compress a file to Gzip format
//  while setting custom metadata such as comment, filename,
//  compression level, and last-modified date.

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

//  Set custom Gzip properties:
gzip.Comment = @"Example Gzip file created with Chilkat";
gzip.Filename = @"custom_name.txt";
gzip.CompressionLevel = [NSNumber numberWithInt:9];
gzip.LastModStr = @"Wed, 1 Apr 2025 12:45:26 -0500";

//  The file to be compressed:
NSString *inputFile = @"example.txt";
NSString *outputFile = @"example.txt.gz";

//  Compress the file:
success = [gzip CompressFile: inputFile destPath: outputFile];
if (success == NO) {
    NSLog(@"%@",gzip.LastErrorText);
    return;
}

NSLog(@"%@",@"Compression successful.");
NSLog(@"%@%@",@"Gzip file created: ",outputFile);