Objective-C

Cancel Async Task if not Completed after a Max Time

See more Async Examples

Demonstrates how to wait a maximum amount of time for an asynchronous task to completed. If not completed in the allotted amount of time, the task is cancelled. Objective-C

#import <CkoHttp.h>
#import <NSString.h>
#import <CkoTask.h>

BOOL success = NO;

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

CkoHttp *http = [[CkoHttp alloc] init];

// Set some timeouts, in seconds:
http.ConnectTimeout = [NSNumber numberWithInt:15];
http.ReadTimeout = [NSNumber numberWithInt:15];

// Wait a max time of 2 seconds for the task.
// In this example, it's an unreasonably small amount of time,
// which means the task will get cancelled.
int waitMaxMs = 2000;

// We're just going to download for 2 seconds and then cancel.
// Substitute your own URL with a large enough file for testing..
NSString *downloadUrl = @"http://download.mono-project.com/archive/4.6.1/windows-installer/mono-4.6.1.5-gtksharp-2.12.38-win32-0.msi";

CkoTask *task = [http DownloadAsync: downloadUrl saveToPath: @"qa_output/mono.msi"];
[task Run];

// Wait a maximum of waitMaxMs for the task (i.e. the HTTP download) to complete.
// The Wait method returns when the task has been canceled, aborted, or completed, or when the max allotted time has passed.
[task Wait: [NSNumber numberWithInt: waitMaxMs]];

// At this point, the download may or may not have completed.  
// Rather than checking the Task status, we can call task.Cancel because
// if the Task is no longer running (because it already completed, was canceled or aborted), then the 
// call to Cancel is a NO-OP (meaning it does nothing and the Task's status is unaffected).
// Also, task.Cancel returns YES if the task was in the "queued" or "running" state and was canceled or aborted. 
// The method returns NO if the task has any other status.
BOOL wasCanceled = [task Cancel];
if (wasCanceled == YES) {
    NSLog(@"%@",@"The HTTP download took too long and was canceled.");
}
else {
    // Find out what happened.
    if ([task.StatusInt intValue] == 7) {
        // The task completed, which means the background thread's call to Download completed
        // with success or failure.  Find out which...
        success = [task GetResultBool];
        if (success == YES) {
            NSLog(@"%@",@"Download successful!");
        }
        else {
            NSLog(@"%@",@"Download failed prior to waitMaxMs...");
            NSLog(@"%@",task.ResultErrorText);
        }

    }
    else {
        // The task must've been canceled or aborted by some other means..
        NSLog(@"%@%@",@"Task did not complete.  Final status: ",task.Status);
    }

}