gistfile1.m

#include "copyfile.h"

typedef enum {
    _NotStarted = 0,
    _InProgress,
    _Finished,
} _State;

@implementation BAVAppDelegate
{
    copyfile_state_t _copyfileState;
    _State _state;
    NSTimer *_progressTimer;
}

- (void)applicationDidFinishLaunching:(NSNotification *)notification
{
    [self performSelectorInBackground:@selector(copyFile) withObject:nil];
    _progressTimer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(outputProgress) userInfo:@{} repeats:YES];
}

- (void)copyFile
{
    NSLog(@"Will start copying");

    int returnCode;
    _copyfileState = copyfile_state_alloc();
    {
        const char *fromPath = [[@"~/Desktop/bigfile.mkv" stringByExpandingTildeInPath] UTF8String];
        const char *toPath = [[@"~/Desktop/bigfile_copy.mkv" stringByExpandingTildeInPath] UTF8String];

        _state = _InProgress;
        {
            returnCode = copyfile(fromPath, toPath, _copyfileState, COPYFILE_ALL);
        }
        _state = _Finished;
        [_progressTimer performSelectorOnMainThread:@selector(invalidate) withObject:nil waitUntilDone:YES];
        _progressTimer = nil;
    }
    copyfile_state_free(_copyfileState);

    NSLog(@"Did finish copying with return code %d", returnCode);
}

- (void)outputProgress
{
    switch (_state) {
        case _NotStarted:
            NSLog(@"Not started yet");
            break;
        case _Finished:
            NSLog(@"Finished");
            break;
        case _InProgress: {
            off_t copiedBytes;
            const int returnCode = copyfile_state_get(_copyfileState, COPYFILE_STATE_COPIED, &copiedBytes);
            if (returnCode == 0)
                NSLog(@"Copied %@ so far", [NSByteCountFormatter stringFromByteCount:copiedBytes countStyle:NSByteCountFormatterCountStyleFile]);
            else
                NSLog(@"Could not retrieve copyfile state");
            break;
        }
    }
}

@end