Retrieve current branch OSX

gistfile1.m

- (NSString *)projectDirectoryPath
{
    NSWindowController *currentWindowController = [[NSApp mainWindow] windowController];
    id document = [currentWindowController document];
    if (currentWindowController && [document isKindOfClass:NSClassFromString(@"IDEWorkspaceDocument")]) {
        NSURL *workspaceDirectoryURL = [[[document valueForKeyPath:@"_workspace.representingFilePath.fileURL"] URLByDeletingLastPathComponent] filePathURL];
        if(workspaceDirectoryURL) {
            return [workspaceDirectoryURL path];
        }
    }
    
    return nil;
}

- (void)retrieveCurrentBranch
{
    NSTask *task = [[NSTask alloc] init];
    [task setLaunchPath:@"/usr/bin/git"];
    [task setCurrentDirectoryPath:[self projectDirectoryPath]];
    
    NSMutableArray *arguments = [NSMutableArray array];
    [arguments addObject:@"describe"];
    [arguments addObject:@"--contains"];
    [arguments addObject:@"--all"];
    [arguments addObject:@"HEAD"];
    [task setArguments:arguments];
    
    NSPipe *outputPipe = [NSPipe pipe];
    [task setStandardOutput:outputPipe];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(currentBranchReadCompleted:) name:NSFileHandleReadToEndOfFileCompletionNotification object:[outputPipe fileHandleForReading]];
    [[outputPipe fileHandleForReading] readToEndOfFileInBackgroundAndNotify];
    
    [task launch];
}

#pragma mark - Notifications

- (void)currentBranchReadCompleted:(NSNotification *)notification
{
    [[NSNotificationCenter defaultCenter] removeObserver:self name:NSFileHandleReadToEndOfFileCompletionNotification object:[notification object]];
    
    NSData *data = [[notification userInfo] objectForKey:NSFileHandleNotificationDataItem];
    NSString *currentBranchName = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    
    NSLog(@"Current Branch: %@", currentBranchName);
}