swift - UICollectionView 委托(delegate)方法未正确调用

Question

我有一个 UICollectionView，在每个单元格中，我在 cellForItemAtIndexPath 中从数组设置 UILabel 的文本:

let array = ["New York City", "Chicago", "San Francisco"]

单元格在屏幕上显示正确的标签，但是当我尝试在 didSelectItemAtIndexPath 中记录标签的值时，它将值记录为 nil。如果我尝试在 didSelectItemAtIndexPath 中执行任何其他操作(例如更改单元格的不透明度)，则不会执行任何更改。

这里可能出了什么问题？

<小时/>

相关代码:

View Controller 具有父类(super class)UICollectionViewDataSource和UICollectionViewDelegateFlowLayout。

Collection View 单元格的类声明:

class PickerCell: UICollectionViewCell {
var label = UILabel()

override init(frame: CGRect) {
    super.init(frame: frame)
    contentView.backgroundColor = UIColor.clearColor()

    label.frame = contentView.bounds
    label.textColor = UIColor.whiteColor()
    label.textAlignment = NSTextAlignment.Left
    label.font = font.body
    contentView.addSubview(label)
}

required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
}
}

创建 Collection View :

func createPickerView() {
    let pickerFlowLayout: UICollectionViewFlowLayout = PickerLocationFlowLayout()
    pickerFlowLayout.itemSize = CGSize(width: screenSize.width, height: 40)
    pickerFlowLayout.minimumLineSpacing = 0

    let pickerView: UICollectionView
    pickerView = UICollectionView(frame: CGRectMake(0, 0, screenSize.width, screenSize.height), collectionViewLayout: pickerFlowLayout)
    pickerView.registerClass(PickerCell.self, forCellWithReuseIdentifier: "PickerCellId")
    pickerView.delegate = self
    pickerView.dataSource = self
    self.view.addSubview(pickerView)
}

选择单元格:

func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
    let cell = collectionView.dequeueReusableCellWithReuseIdentifier("PickerCellId", forIndexPath: indexPath) as! PickerCell
    print("indexpath: \(indexPath.row), label: \(cell.label.text)")
    // Prints the correct row number, but nil for the label.
}

Answer 1

事实证明我犯了一个愚蠢的错误。在 didSelectItemAtIndexPath 中，我调用了 dequeueReusableCellWithReuseIdentifier，我应该调用 cellForItemAtIndexPath。