Objective-C

Get a Remote File's Last-Modified Time

Demonstrates the Chilkat SFtp.GetFileLastModifiedStr method, which returns a remote file's last-modified date and time. The arguments are the remote path (or handle), whether symbolic links are followed, and whether the first argument is a handle.

Background: The last-modified time is the workhorse timestamp — it updates whenever a file's contents change and is what incremental-sync logic compares to decide whether a file needs re-transferring. It is the most reliably supported of the three across servers and filesystems, which is why timestamp-based sync keys off it.

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Objective-C

#import <CkoSFtp.h>
#import <NSString.h>

BOOL success = NO;

//  Demonstrates the SFtp.GetFileLastModifiedStr method, which returns a remote file's last-modified
//  date and time.  The 1st argument is the remote path (or handle), the 2nd selects whether
//  symbolic links are followed, and the 3rd indicates whether the 1st argument is a handle.

CkoSFtp *sftp = [[CkoSFtp alloc] init];

//  Connect, authenticate, and initialize the SFTP subsystem.
int port = 22;
success = [sftp Connect: @"sftp.example.com" port: [NSNumber numberWithInt: port]];
if (success == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

//  Normally you would not hard-code the password in source.  You should instead obtain it
//  from an interactive prompt, environment variable, or a secrets vault.
NSString *password = @"mySshPassword";

success = [sftp AuthenticatePw: @"mySshLogin" password: password];
if (success == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

success = [sftp InitializeSftp];
if (success == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

//  The 2nd argument (bFollowLinks) selects whether a symbolic link is followed to its target.
//  The 3rd argument (bIsHandle) is false here because the 1st argument is a path, not an
//  open handle.
BOOL bFollowLinks = YES;
BOOL bIsHandle = NO;

NSString *lastModified = [sftp GetFileLastModifiedStr: @"subdir/report.pdf" bFollowLinks: bFollowLinks bIsHandle: bIsHandle];
if (sftp.LastMethodSuccess == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

NSLog(@"%@%@",@"Last modified: ",lastModified);

[sftp Disconnect];