Swift UIView内存使用情况并处理许多子视图

Question

I'm making a Word Search app, where I display a large 14x14 grid of letters. Right now, I display each letter using its own UILabel as such:

for _ in 0..<14 {
  for _ in 0..<14 {
    let letterLabel = UILabel()
    letterLabel.text = randomLetter()
    addSubview(letterLabel)
  }
}

However, I'm wondering if I would be better off structuring my code as such:

let lettersLabel = UILabel()
for _ in 0..<14 {
  for _ in 0..<14 {
    letterLabel.text += randomLetter() + " "
  }
  letterLabel.text += "\n"
}
addSubview(letterLabel)

My theory is that this will reduce my app's memory footprint, although I can't find any documentation about exactly how much memory each UILabel will take up.

But, I'm wondering, how much memory would the latter approach actually save me? And which approach is standard/preferred in iOS development? Or, is there a third approach I haven't thought of?

I feel that the latter approach is better from a performance standpoint, but would greatly complicate the code when it comes to spacing the letters evenly across the screen and determining which letter is tapped.

(Note: This question dramatically simplifies my actual code to highlight the problem area)

Answer 1

Since you want to know which letter is tapped, I would recommend using a collection view. Here is a sample implementation:

private let reuseIdentifier = "Cell"

class CollectionViewController: UICollectionViewController, UICollectionViewDelegateFlowLayout {

    //Here I am generating an array of 14*14 strings since I don't have access to the randomLetter() function
    let elements = (0..<(14 * 14)).map { String($0) }

    override func viewDidLoad() {
        super.viewDidLoad()

        // Register cell classes
        self.collectionView!.register(CollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)
    }

    override func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }

    override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return elements.count
    }

    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath) as! CollectionViewCell
        cell.label = UILabel(frame: cell.bounds)
        cell.label.text = elements[indexPath.row] //In your case you would use: cell.label.text = randomLetter()
        cell.label.font = UIFont(name: "helvetica", size: 10)
        cell.label.textAlignment = .center
        cell.addSubview(cell.label)
        return cell
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        let size = CGSize(width: self.view.frame.size.width/14, height: self.view.frame.size.width/14)
        return size
    }

    override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        let cell = collectionView.cellForItem(at: indexPath) as! CollectionViewCell
        print(String(describing: cell.label.text))
    }
}

Where CollectionViewCell is a custom UICollectionViewCell defined as follows:

class CollectionViewCell: UICollectionViewCell {
    var label: UILabel!
}