重新加载集合视图数据时对成员'collectionView(_:numberOfItemsInSection:)'的不明确引用

Question

在我一直在写的一个应用程序中，其中一个选项卡包含一个集合视图，最初填充了虚拟信息，但一旦用户在另一个选项卡中输入一些信息，应该被替换。然而，当我尝试使用self.collectionView?.reloadData() Xcode说Ambiguous reference to member 'collectionView(_:numberOfItemsInSection:)'。删除了与获取槽数据相关的代码。有人知道为什么它不起作用吗?

//
//  FirstViewController.swift
import UIKit
import Alamofire
class FirstViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {
    let reuseIdentifier = "cell" // also enter this string as the cell identifier in the storyboard
    var items = ["1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32", "33", "34", "35", "36", "37", "38", "39", "40", "41", "42", "43", "44", "45", "46", "47", "48"]

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
    self.collectionView?.reloadData()
}
// MARK: - UICollectionViewDataSource protocol
// tell the collection view how many cells to make
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return self.items.count
}
// make a cell for each cell index path
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    // get a reference to our storyboard cell
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath as IndexPath) as! MyCollectionViewCell
    // Use the outlet in our custom class to get a reference to the UILabel in the cell
    cell.myLabel.text = self.items[indexPath.item]
    cell.backgroundColor = UIColor.white
    cell.layer.borderColor = UIColor.white.cgColor
    cell.layer.borderWidth = 5
    cell.layer.cornerRadius = 8// make cell more visible in our example project
    return cell
}
// MARK: - UICollectionViewDelegate protocol
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    // handle tap events
    print("You selected cell #(indexPath.item)!")
}

}

Answer 1

您正在使用UIViewController而不是UICollectionViewController所以您不会免费获得collectionView属性。你需要从故事板中拖进一个outlet，并命名为@IBOutlet var collectionView: UICollectionView!.