AllWorkoutsVC中CollectionView的didSelectItemAt传值至VideoViewVC失败

Hey Marcus, let's troubleshoot why your videoCode isn't getting passed to VideoViewVC when tapping a collection view cell. This is a super common issue, so let's break down the most likely fixes step by step:

1. Verify you're correctly instantiating VideoViewVC (and setting the variable before navigating) #

The most frequent mistake here is either misinstantiating the view controller, or setting the variable after pushing/presenting it. Here's how to do it right depending on your setup:

If using Storyboards:

override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    // 1. Grab the selected videoCode from your data source
    let selectedVideoCode = yourWorkoutsArray[indexPath.item].videoCode
    print("Selected code: \(selectedVideoCode)") // Add this to confirm you're getting valid data
    
    // 2. Safely instantiate VideoViewVC from your storyboard
    guard let videoVC = storyboard?.instantiateViewController(withIdentifier: "VideoViewVC") as? VideoViewVC else {
        print("Failed to load VideoViewVC — check your storyboard identifier!")
        return
    }
    
    // 3. Set the variable BEFORE navigating
    videoVC.myPassVideoCode = selectedVideoCode
    
    // 4. Navigate to the new VC
    navigationController?.pushViewController(videoVC, animated: true)
}

If using pure code initialization:

Make sure your VideoViewVC has a proper initializer, and you're setting the variable upfront:

// In AllWorkoutsVC's didSelectItemAt
let selectedVideoCode = yourWorkoutsArray[indexPath.item].videoCode
let videoVC = VideoViewVC()
videoVC.myPassVideoCode = selectedVideoCode
navigationController?.pushViewController(videoVC, animated: true)

2. Double-check the variable declaration in VideoViewVC #

Ensure myPassVideoCode is accessible and mutable — don't mark it as private or let (unless you're using a custom initializer):

class VideoViewVC: UIViewController {
    // Correct: mutable, accessible from other VCs in the same target
    var myPassVideoCode: String?

    override func viewDidLoad() {
        super.viewDidLoad()
        // Test if the variable came through
        if let code = myPassVideoCode {
            print("Received video code: \(code)")
        } else {
            print("No video code received!")
        }
    }
}

3. If using Storyboard Segues (instead of manual instantiation) #

If you're triggering a segue directly from the collection view cell in Storyboard, use prepare(for:sender:) to pass data:

// First, trigger the segue in didSelectItemAt
override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    performSegue(withIdentifier: "GoToVideoView", sender: indexPath)
}

// Then pass data in prepare(for:)
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    guard segue.identifier == "GoToVideoView",
          let videoVC = segue.destination as? VideoViewVC,
          let indexPath = sender as? IndexPath else {
        return
    }
    videoVC.myPassVideoCode = yourWorkoutsArray[indexPath.item].videoCode
}

Just make sure your segue's identifier matches exactly what's in your code, and the segue connects AllWorkoutsVC to VideoViewVC.

Quick Troubleshooting Steps #

• Add print statements to confirm selectedVideoCode has a valid value before passing it.
• Check for typos in myPassVideoCode (case sensitivity matters in Swift!).
• Ensure you're not accidentally creating a new instance of VideoViewVC after setting the variable (this is an easy slip-up).

If none of these fix it, feel free to share more code snippets (like your data source setup or VideoViewVC initialization) and we can dig deeper.

内容的提问来源于stack exchange，提问作者Marcus Levi