CODEWITHSUNDEEP
cmacoscocoasystem
Justin
Justin

Reputation: 2142

Cocoa system() progress?

I am creating an application that must use the system(const char*) function to do some "heavy lifting", and I need to be able to give the user a rough progress percentage. For example, if the OS is moving files for you, it gives you a progress bar with the amount of data moved and the amount of data to move displayed on the window. I need something like that. How can this be done?

Edit: Basically, I give the user the option to save files in a compressed format. If they do so, it saves normally then runs this code:

char* command = (char*)[[NSString stringWithFormat:@"tar -jcvf %@.tar.bz2 %@", saveurl.path, filename] cStringUsingEncoding:NSUTF8StringEncoding];
system(command);

Sometimes this takes a little while (the app deals with video files), so I want to be able to give them an estimated completion time.

Upvotes: 2

Views: 178

Answers (2)

Randy Howard
Randy Howard

Reputation: 2156

You would need a command line program that has a way of communicating progress information back to your application (or perhaps simply write progress info to a log file that you parse in your cocoa app). Are you sure you really need to do this?

For your edited example, you might consider just putting up some sort of spinner or hourglass type UI indicator to show them that the write is in progress, while allowing them to continue with other work. You can't predict archive creation time, especially when you add compression to it.

Upvotes: 2

Ken Thomases
Ken Thomases

Reputation: 90651

I am creating an application that must use the system(const char*) function to do some "heavy lifting"

No, it doesn't have to use system() as such. In fact, it shouldn't. There are plenty of other APIs for running subprocesses, almost all of which will be better. In Cocoa, the most obvious better option is NSTask.

In any case, there's nothing that can tell how much progress a subprocess is making except that subprocess itself. If the program you're running doesn't provide a means for reporting progress, there's little hope. Nothing else can even divine what the purpose or goal of the subprocess is, let alone judge how far along it is to meeting that goal.

Even if the program does report progress, you'll need a means to receive that information. system() doesn't allow for that. NSTask does, as would popen() or manually forking and execing the program.

Upvotes: 5

Related Questions