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Objective-C

Wait for a Socket to Become Writable

See more Socket/SSL/TLS Examples

Demonstrates Socket.SelectForWriting, which waits for the socket, or sockets in a socket set, to become writable. It returns 1 if writable, 0 on timeout, or -1 on error.

Background. A timeoutMs of 0 performs a nonblocking poll. This is useful before attempting to send when the peer may be applying flow control.

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Objective-C
#import <CkoSocket.h>

BOOL success = NO;

CkoSocket *socket = [[CkoSocket alloc] init];

//  Connect to the server using TLS.
BOOL bTls = YES;
int maxWaitMs = 5000;
success = [socket Connect: @"example.com" port: [NSNumber numberWithInt: 5000] ssl: bTls maxWaitMs: [NSNumber numberWithInt: maxWaitMs]];
if (success == NO) {
    NSLog(@"%@",socket.LastErrorText);
    return;
}

//  Wait up to 5 seconds for the socket (or sockets in a socket set) to become writable.  Returns 1 if
//  writable, 0 on timeout, or -1 on error.
int ready = [[socket SelectForWriting: [NSNumber numberWithInt: 5000]] intValue];
if (ready < 0) {
    NSLog(@"%@",socket.LastErrorText);
    return;
}

if (ready != 1) {
    NSLog(@"%@",@"The socket did not become writable before the timeout.");
    return;
}

NSLog(@"%@",@"The socket is ready for writing.");