如何使用panGesture从firstViewController的顶部移动secondViewController？

Question

我正在尝试使用pan Gesture将secondViewController从第一个ViewController停止移开，但我遇到了一个问题......

当我开始移动secondViewController时，黑色屏幕显示在控制器后面，而不是firstViewController（正如我所料），我不知道如何解决这个问题......

这是代表我的问题的代码......

firstVC在这里..

import UIKit

class mainController: UIViewController {

    let tapGestureRecognizer = UITapGestureRecognizer()
    let secondVC = SecondViewController()

    override func viewDidLoad() {
        super.viewDidLoad()

        tapGestureRecognizer.addTarget(self, action: #selector(goToSecondVC))

        view.backgroundColor = UIColor.red
        view.addGestureRecognizer(tapGestureRecognizer)
    }

    @objc func goToSecondVC(){
        present(secondVC, animated: true, completion: nil)
    }        
}

和第二个VC在这里..

import UIKit

class SecondViewController: UIViewController {

    let panGesture = UIPanGestureRecognizer()

    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = UIColor.green

        panGesture.addTarget(self, action: #selector(moveView))

        view.addGestureRecognizer(panGesture)
    }

    @objc func moveView(pan: UIPanGestureRecognizer){
        let translation = pan.translation(in: view)

        if pan.state == .began{
            print("began")

        } else if pan.state == .changed {

            view.frame.origin.x += translation.x

            pan.setTranslation(CGPoint.zero, in: view)
        } else if pan.state == .ended{

            print("ended")                
        }
    }
}

为什么在第二个ViewController之后第二个视图控制器后面有黑屏？

Answer 1

你只需要正确设置你的SecondViewController的modalPresentationStyle ...

@objc func goToSecondVC(){
    secondVC.modalPresentationStyle = .overCurrentContext
    present(secondVC, animated: true, completion: nil)
}