Re: Copying large files with progress indicator

FROM : Shawn Erickson
DATE : Tue Aug 01 17:51:18 2006

On Aug 1, 2006, at 8:38 AM, Mike Abdullah wrote:

>
> 10.4 only is fine for me.  I've had a look at FSCopyObjectAsync, 
> and after a search around, found Apple's nice FSFileOperation 
> sample code:
>
> http://developer.apple.com/samplecode/FSFileOperation/
>
> I've got a quick simple project up and running using this, however, 
> I wonder if someone could help clarify something for me.  My code is:
>
> - (IBAction)doCopy:(id)sender
> {
>     OSStatus err;
>     FSRef  sourceFileRef, destinationDirectoryRef;
>     
>     // Build the parameters
>     FSFileOperationRef fileOp = FSFileOperationCreate
> (kCFAllocatorDefault);
>     
>     FSPathMakeRef((UInt8 *)[@"/Users/dev/Desktop/test.dmg" 
> fileSystemRepresentation], &sourceFileRef, NULL);
>     
>     FSPathMakeRef((UInt8 *)[@"/Users/dev/Desktop/Copy/" 
> fileSystemRepresentation], &destinationDirectoryRef, NULL);
>     
>     OptionBits options = kFSFileOperationDefaultOptions;
>     
>     
>     // Do the copy
>     err = FSCopyObjectAsync(fileOp, &sourceFileRef, 
> &destinationDirectoryRef, NULL, options, NULL, 0.01, NULL);
>     
>     while (YES)
>     {
>     CFRunLoopRunInMode(kCFRunLoopDefaultMode, 5.0, true);
>     
>     CFDictionaryRef infoDict2;
>     (void) FSFileOperationCopyStatus(fileOp, NULL, NULL, &err, 
> &infoDict2, NULL);
>     
>     NSLog(@"%@", (NSDictionary *)infoDict2);
>     }
> }
>
> Now obviously, I need to do this in a separate thread which isn't a 
> problem.  However, what I don't really understand is what exactly 
> goes on with the CFRunLoopRunInMode call.  It seems that during the 
> duration of this method, that's when a chunk of file copying is 
> actually done, but once I stick the code in a thread, should I 
> really use this, or is there something better?


You don't actually have to do this in a separate thread. You can 
register a callback and execute this operation on your main thread 
(the main thread in a Cocoa application has an active runloop). You 
will get callbacks from your main runloop as the copy progresses and 
when it finishes.

The example above is written to be run from a secondary thread and 
doesn't leverage the callback capability (why it is running its own 
runloop periodically).

Review the docs on runloops (CFRunLoop and NSRunLoop) if you don't 
understand what those are.

-Shawn