Objective-C

Read Text at a String Offset from a Remote SFTP File

Demonstrates the Chilkat SFtp.ReadFileText64s method, which is like ReadFileText64 but takes the byte offset as a decimal string. The arguments are the handle, the offset string, the maximum number of bytes, and the charset.

Background: The string-offset read exists for the same reason as its write counterpart: it lets code in languages without convenient 64-bit integers still address positions in very large files by supplying the offset as text. Functionally it is identical to the int64 version.

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Objective-C

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

BOOL success = NO;

//  Demonstrates the SFtp.ReadFileText64s method, which is like ReadFileText64 but takes the byte
//  offset as a decimal string.  The 1st argument is the handle, the 2nd is the offset string, the
//  3rd is the maximum number of bytes, and the 4th is the charset.

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;
}

NSString *handle = [sftp OpenFile: @"subdir/hugefile.dat" access: @"readOnly" createDisp: @"openExisting"];
if (sftp.LastMethodSuccess == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

//  Supplying the offset as a string is convenient in languages without a native 64-bit integer.
NSString *offset = @"5000000000";
int numBytes = 6;
NSString *text = [sftp ReadFileText64s: handle offset: offset numBytes: [NSNumber numberWithInt: numBytes] charset: @"utf-8"];
if (sftp.LastMethodSuccess == NO) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

NSLog(@"%@",text);

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

[sftp Disconnect];