Question

我试图在ViewControllers之间传递数据而我没有使用故事板，所以我不能使用prepareForSegue方法，这就是我所做的：

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    var vc = productDetailViewController()
    self.navigationController?.pushViewController(productDetailViewController(), animated: true)
    vc.product = self.shoes[indexPath.row]
}

Answer 1

你在这里犯了两个错误：

1）尝试在vc中设置值，但发送一个新的视图控制器实例。

2）在按下控制器之后为控制器设置值。

所以，试试如下：

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

var vc = productDetailViewController()

vc.product = self.shoes[indexPath.row]

self.navigationController?.pushViewController(vc,     animated: true)

}

Answer 2

交换最后两行......您的productDetailViewController可能正在寻找初始化时的产品数据，这已经在推送时已经发生过。

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

    // instantiate the new VC
    var vc = productDetailViewController()

    // set the data in the new VC first
    vc.product = self.shoes[indexPath.row]

    // then "show" the new VC --- NOT a new instance of productDetailViewController()
   //self.navigationController?.pushViewController(productDetailViewController(), animated: true)</s>
    self.navigationController?.pushViewController(vc, animated: true)
}

在ViewControllers之间传递数据

2 个答案: