Ios A，B，ViewController传递数据

class AViewController: UIViewController{
    @IBAction func nextB(_ sender: UIButton){
        let bViewController = UIStoryboard.init(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "BViewController") as! BViewController
        bViewController.modalPresentationStyle = .fullScreen
        bViewController.delegate = self
        self.present(bViewController, animated: true, completion:nil)
    }
}

extension AViewController:BDelegate{
    func bContext(context: String) {
        print("回传内容" + context)
    }
}

protocol BDelegate{
    func bContext(context: String)
}

var delegate: BDelegate!
class BViewController: UIViewController{
    @IBAction func editBackBtn(_ sender: UIButton){
        self.delegate.bContext(context: "传入数据到A界面")
    }
}