Swift4中UITableView.reloadData不更新及ActivityIndicator未移除问题求助

Hey there, let's work through these two frustrating problems you're facing. I've run into similar UI update and indicator cleanup issues before, so here's what's likely going wrong and how to fix it:

1. Activity Indicator & Background View Won't Disappear #

The root cause here is almost certainly in your UIView extension's activityStopAnimating() method. If the method only calls stopAnimating() on the indicator but doesn't remove the indicator and its background view from the view hierarchy, they'll stay visible even after the animation stops.

Fix: Update Your Extension to Clean Up Views #

Make sure your stop method actively removes the views you added when starting the indicator. Using tags is a simple way to track these views:

extension UIView {
    func activityStartAnimating() {
        // Create and configure background view
        let backgroundView = UIView(frame: bounds)
        backgroundView.backgroundColor = UIColor.black.withAlphaComponent(0.5)
        backgroundView.tag = 999 // Unique tag to identify it later
        
        // Create and configure activity indicator
        let indicator = UIActivityIndicatorView(style: .whiteLarge)
        indicator.center = backgroundView.center
        indicator.tag = 1000 // Unique tag for the indicator
        
        backgroundView.addSubview(indicator)
        addSubview(backgroundView)
        
        indicator.startAnimating()
    }
    
    func activityStopAnimating() {
        // Find and remove the background view
        if let backgroundView = viewWithTag(999) {
            backgroundView.removeFromSuperview()
        }
        
        // Find and clean up the indicator (extra safety)
        if let indicator = viewWithTag(1000) {
            indicator.stopAnimating()
            indicator.removeFromSuperview()
        }
    }
}

This ensures both the indicator and its background are fully removed from your view when you call activityStopAnimating().

2. Collection View Isn't Updating #

There are a few possible culprits here, but the most common one is using DispatchQueue.main.sync instead of async, plus a few quick checks to validate your setup:

Fix 1: Replace sync with async for UI Updates #

Using DispatchQueue.main.sync can cause deadlocks (especially if your API callback is accidentally running on the main thread already) and block UI updates. Always use async for UI-related work:

// Inside your API completion handler
yourAPIFetchCall { [weak self] fetchedData in
    guard let self = self else { return }
    
    // Populate your data array (make sure it's a var, not let!)
    self.yourDataArray = fetchedData
    
    // Switch to main thread safely with async
    DispatchQueue.main.async {
        self.CapsulleCollectionView.reloadData()
        self.view.activityStopAnimating()
    }
}

Fix 2: Validate Your Collection View Setup #

Double-check these critical points:

• Ensure yourDataArray is declared as a variable (var yourDataArray: [YourDataType] = []) — if it's a constant (let), it can't be updated.
• Confirm your collection view's data source methods use this array:

  func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
      return yourDataArray.count // Not a hardcoded number!
  }
  
  func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
      let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "YourCellID", for: indexPath) as! YourCellType
      let item = yourDataArray[indexPath.row]
      // Configure cell with item data
      return cell
  }
  

• Verify your collection view's IBOutlet is properly connected in Interface Builder (check that CapsulleCollectionView isn't nil by printing it before calling reloadData()).
• Make sure you've set the collection view's dataSource and delegate to self (either in IB or in viewDidLoad()).

内容的提问来源于stack exchange，提问作者abdul sathar