Displaying file copy progress using FSCopyObjectAsync

Question

It appears after much searching that there seems to be a common problem when trying to do a file copy and show a progress indicator relative to the amount of the file that h

Answer 1

You can do this by using the last parameter to FSCopyObjectAsync(), which is a struct of type FSFileOperationClientContext. One of the fields of that struct is info, which is a void* parameter that you can basically use as you see fit. Whatever you assign to that field of the struct you pass into FSCopyObjectAsync() will be passed in turn to your callback function as the last info function parameter there. A void* can be anything, including a pointer to an object, so you can use that to pass the instance of your object that you want to handle the callback.

The setup code would look like this:

FSFileOperationClientContext clientContext = {0}; //zero out the struct to begin with

clientContext.info = myProgressIndicator;
//All the other setup code
status = FSCopyObjectAsync (fileOp,
         &source,
         &destination, // Full path to destination dir
         targetFilename,
         kFSFileOperationDefaultOptions,
         statusCallback,
         1.0,
         &clientContext);

Then, in your callback function:

static void statusCallback (FSFileOperationRef fileOp,
       const FSRef *currentItem,
       FSFileOperationStage stage,
       OSStatus error,
       CFDictionaryRef statusDictionary,
       void *info )
{
    NSProgressIndicator* fileProgressIndicator = (NSProgressIndicator*)info;
    [fileProgressIndicator setDoubleValue:(double)floatBytesCompleted];
    [fileProgressIndicator displayIfNeeded];
}