自定义 UICollectionCell 的 nil 标签 [英] nil label for custom UICollectionCell

问题描述

编辑:似乎与这个问题相同
我使用自定义布局和单元格制作了集合视图，但我的单元格的位置有点偏离，所以我决定给它们编号，以便我可以更轻松地调试它.我跟着这个人的answer使用标签为我的单元格编号.不知何故 myLabel 为零并导致我的应用程序崩溃.

EDIT: seems like same question as this
I made collection view with custom layout and cell but my cell's positions were a little off so I decided to number them so that I could debug it easier. I followed this guy's answer to number my cell using labels. Somehow myLabel was nil and caused my app to crash.

我相信我已经正确连接了插座，但也许有人可以提供一个列表让我检查我是否做错了什么.

I believe I have connected the outlets correctly but maybe someone could provide a list for me to check if I am doing anything wrong.

import UIKit

class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {

  @IBOutlet var gridView: UICollectionView!

  private let reuseIdentifier = "DesignCell"
  private let numberOfSections = 1
  private let numberOfCircles = 48

  override func viewDidLoad() {
    super.viewDidLoad()
    self.gridView.registerClass(MyCell.self, forCellWithReuseIdentifier: reuseIdentifier)
  }

  func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
    return numberOfSections
  }

  func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return numberOfCircles
  }

  func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {

    let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! MyCell

    cell.myLabel.text = String(indexPath.item) // myLabel is nil and causes a crash
    return cell
  }

  override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
  }

}

GridLayout(我的自定义布局)

import UIKit
import Darwin

class GridLayout: UICollectionViewLayout {

  private let numberOfColumns = 12
  private let numberOfRows = 4

  private var cache = [UICollectionViewLayoutAttributes]()
  private var contentHeight: CGFloat = 0
  private var contentWidth: CGFloat {
    let insets = collectionView!.contentInset
    return CGRectGetWidth(collectionView!.bounds) - insets.left - insets.right
  }

  override func prepareLayout() {
    // some calculation i did for my cells
  }

  override func collectionViewContentSize() -> CGSize {
    return CGSize(width: contentWidth, height: contentHeight)
  }

  override func layoutAttributesForElementsInRect(rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
    var layoutAttributes = [UICollectionViewLayoutAttributes]()

    for attr in cache {
      if CGRectIntersectsRect(attr.frame, rect) {
        layoutAttributes.append(attr)
      }
    }
    return layoutAttributes
  }
}

我的细胞

import UIKit

class MyCell : UICollectionViewCell {

  @IBOutlet weak var myLabel: UILabel!

}

推荐答案

尝试在 ViewController 类中的 viewDidLoad() 中删除这一行:

Try to remove this line within viewDidLoad() in your ViewController class:

self.gridView.registerClass(MyCell.self, forCellWithReuseIdentifier: reuseIdentifier)

不需要它，因为您已经在 Storyboard 中创建了 UICollectionView，连接到您的数据源和委托，并且您已经添加了所有必需的方法:

It's not needed since you have created your UICollectionView in Storyboard, connected to your dataSource and delegate, and you have added all the required methods:

• numberOfItemsInSection
• cellForItemAtIndexPath

这篇关于自定义 UICollectionCell 的 nil 标签的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！