Async execution of shell command not working properly

Question

So, this is my code :

- (void)runCmd:(NSString *)cmd withArgs:(NSArray *)args
{
    NSLog(@\"\\nRunning ::\\n\\tCmd : %@\\n\\tArgs : %@\",cmd, args);
    [theSpi         


        

Answer 1

There's a new API since 10.7, so you can avoid using NSNotifications.

task.standardOutput = [NSPipe pipe];
[[task.standardOutput fileHandleForReading] setReadabilityHandler:^(NSFileHandle *file) {
    NSData *data = [file availableData]; // this will read to EOF, so call only once
    NSLog(@"Task output! %@", [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);

    // if you're collecting the whole output of a task, you may store it on a property
    [self.taskOutput appendData:data];
}];

IMPORTANT:

When your task terminates, you have to set readabilityHandler block to nil; otherwise, you'll encounter high CPU usage, as the reading will never stop.

[task setTerminationHandler:^(NSTask *task) {

    // do your stuff on completion

    [task.standardOutput fileHandleForReading].readabilityHandler = nil;
    [task.standardError fileHandleForReading].readabilityHandler = nil;
}];