let picker = PhotoPickerNavigationController.nc
present(picker, animated: true, completion: nil)

let picker = PhotoPickerNavigationController.nc
picker.config.rootTitle = "Root Title"
picker.config.mediaType = .image
present(picker, animated: true, completion: nil)

class ViewController: UIViewController {
    func showPicker() {        
        let picker = PhotoPickerNavigationController.nc 
        picker.pickerDelegate = self
        present(picker, animated: true, completion: nil)
    }
}

extension ViewController: PhotoPickerDelegate {
    func picker(_ picker: PhotoPickerNavigationController, didSelectAssets assets: [PHAsset]) {
        //do what you want
        //...
        
        //dismiss picker
        picker.dismiss(animated: true, completion: nil)
    }
    
    func picker(_ picker: PhotoPickerNavigationController, shouldSelectAsset: PHAsset, selectedAssets: [PHAsset]) -> Bool {
        //limit number of selections
        if selectedAssets.count >= 2 {
            return false
        }
        return true
    }
}