提出一个控制器解雇它并在Swift中呈现一个不同的控制器

发生此错误的原因是您在解除FirstController后尝试从FirstController呈现SecondController.这不起作用:

self.dismiss(animated: true, completion: {
    let vc = SecondController()

    // 'self' refers to FirstController, but you have just dismissed
    //  FirstController! It's no longer in the view hierarchy!
    self.present(vc, animated: true, completion: nil)
})

这个问题与我昨天回答的问题非常相似.

为您的方案修改,我会建议:

weak var pvc = self.presentingViewController

self.dismiss(animated: true, completion: {
    let vc = SecondController()
    pvc?.present(vc, animated: true, completion: nil)
})