【发布时间】：2020-04-09 04:41:43
【问题描述】：
我试图弄清楚如何在选择集合视图单元格时成功地将数据通过 segue 传递到另一个视图控制器。当我选择一个单元格时，我会崩溃。我以前没有使用集合视图。在我执行之前，我是否正确地准备了 segue？当我选择一个单元格时，我遇到了崩溃。我的数据返回零。如果我推动视图控制器，它工作正常。
// Root view controller, contains collection view that holds different categories. When cell is selected, it should take user to n
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "pushToPosts" {
let vc = segue.destination as? ExplorePostsVC
if let cell = sender as? UICollectionViewCell, let indexPath = collectionView.indexPath(for: cell) {
switch selectedSegmentIndex {
case 0: vc?.style = femaleStyles[indexPath.row]
case 1: vc?.style = maleStyles[indexPath.row]
default: break
}
}
}
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
self.performSegue(withIdentifier: "pushToPosts", sender: self)
}
当我选择一个单元格时，我得到一个致命错误。所有数据在下一个视图控制器中都返回 nil。
// ExplorePostsVC
// To pass images and label
var styleName = ""
var styleDetails = ""
var styleImage: UIImage?
var style: Style!
var headerView: ExplorePostHeader?
override func viewDidLoad() {
super.viewDidLoad()
fetchPosts()
navigationController?.navigationBar.prefersLargeTitles = false
navigationController?.navigationItem.largeTitleDisplayMode = .never
collectionView.delegate = self
collectionView.dataSource = self
}
// Fetch posts based on selected cell
func fetchPosts() {
self.styleDetails = style.details //Thread 1: Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value
self.styleName = style.name
switch style.gender {
case.female:
FEMALE_STYLES_REF.child((style.childValue)).observe(.childAdded) { (snapshot) in
let postId = snapshot.key
Database.fetchPost(with: postId, completion: { (post) in
self.posts.append(post)
self.posts.sort(by: { (post1, post2) -> Bool in
return post1.creationDate > post2.creationDate
})
self.collectionView?.reloadData()
})
}
case .male:
MALE_STYLES_REF.child((style.childValue)).observe(.childAdded) { (snapshot) in
let postId = snapshot.key
Database.fetchPost(with: postId, completion: { (post) in
self.posts.append(post)
self.posts.sort(by: { (post1, post2) -> Bool in
return post1.creationDate > post2.creationDate
})
self.collectionView?.reloadData()
})
}
}
}
【问题讨论】：
-
print(sender)。是细胞吗？在这种情况下，最好强制解开sender和destination以立即发现问题。如果一切都正确连接，代码一定不会崩溃。 -
@vadian 你的评论帮助我到达了我需要去的地方，我发现一些代码没有正确连接到问题中。
style需要清理代码，谢谢！
标签： ios swift uicollectionview segue