How can NSNotification be used to check a the status of an NSTask

Question

How can NSNotification be used to check a the status of an NSTask? I know there are a couple of class methods inside the NSTask but don't really understand how to implement them in a Cocoa application. Can somebody help me?

Answer 1

This blog post, Better way to read from an NSTask, describes how to use NSNotification to recieve notifications from an NSTask.

If you know that your task is not long-running, there is a simpler solution. My answer to another SO question, Execute a terminal command from a Cocoa app, has an example of using NSTask that includes returning the status of the task w/o NSNotification

Answer 2

Thanks Gordon, I have tried out the solution you gave but what's confusing me is when I write the code:

NSPipe *pipe;
pipe = [NSPipe pipe];
[task setStandardOutput: pipe];

NSFileHandle *file;
file = [pipe fileHandleForReading];

[task launch];

NSData *data;
data = [file readDataToEndOfFile];

What is the output data can be return from the task?for my case the console window jus get stuck there and nothing have returned

Answer 3

Task will be stuck when you won't read what it is sending on stdout/stderr. That's why you need to create pipes and set them using setStandardOutput.

Use [NSFileHandle readToEndOfFileInBackgroundAndNotify] and wait for NSFileHandleReadToEndOfFileCompletionNotification. It will give you all data in the callback.