我有一个更新的旧代码示例,但我仍然是新手,无法弄清楚如何解决此错误:
在包含集合视图的类中:
var array = ["Just testing this out"]
现在在UICollectionViewDelegateFlowLayout扩展中:
private func estimateFrameForText(text: String) -> CGRect {
//we make the height arbitrarily large so we don't undershoot height in calculation
let height: CGFloat = 1000
let size = CGSize(width: 398, height: height)
let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
let attributes = [NSAttributedString.Key.font: UIFont.systemFont(ofSize: 17, weight: UIFont.Weight.light)]
return NSString(string: text).boundingRect(with: size, options: options, attributes: attributes, context: nil)
}
也:
private func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
var height: CGFloat = 295
//we are just measuring height so we add a padding constant to give the label some room to breathe!
var padding: CGFloat = 14
//estimate each cell's height
if let text = array[indexPath.item].text {
height = estimateFrameForText(text).height + padding
}
return CGSize(width: 398, height: height) }
这是我得到错误的地方:
if let text = array[indexPath.item].text
这是集合视图单元格类中的UILabel,我不知道在哪里实现:
@IBOutlet weak var TextPosted: UILabel!
答案 0 :(得分:0)
您的测试阵列需要一些调整。尝试将其声明为可选(因为可能是从某处加载的实际数据)。
var array: [String]? = ["Just testing this out", "Another test"]
然后这样:
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return array?.count ?? 0
}
然后在collecitonView sizeForItemAtIndexPath函数中更新if语句:
if let text = array?[indexPath.item]{
}
在旁注中,几天前,我写了一个开源extension来测量诸如此类的字符串大小。
希望这会有所帮助。