- (void)viewDidLoad
{
    [super viewDidLoad];

    self.progressButton.delegate = self;
    self.progressButton.tintColor = [UIColor blueColor];
    self.progressButton.startButtonImage = [UIImage imageNamed:@"download-image"];
    self.progressButton.endButtonImage = [UIImage imageNamed:@"action-image"];
}   

- (void)progressButtonStartButtonTapped:(JNJProgressButton *)button
{
    // Begin doing the download action or whatever asyncronous thing you need to do. Then start updating the progress progerty on the button.
}

- (void)progressButtonEndButtonTapped:(JNJProgressButton *)button
{
    // The button has reached the end of the progress and the user can now do whatever the action needed.
}

- (void)progressButtonDidCancelProgress:(JNJProgressButton *)button
{
    // The user has canceled the progress
}