如何消除使用交互式键盘时出现的resignFirstResponder警告？

Hey there, let's work through this first responder warning you're seeing when using interactive keyboard dismissal in your chat view. I've run into similar quirks before, so here are some actionable fixes to try out:

Understanding the Warning #

First, a quick breakdown: when you dismiss the keyboard interactively by scrolling the table view, iOS tries to tell the current first responder (likely your message input field, or the scroll view itself) to resign its status. But if that view is already being removed from the view hierarchy (or is in a weird state during the dismissal process), the resignFirstResponder() call gets rejected, triggering that annoying warning.

Solution 1: Manually Resign First Responder When Scrolling Starts #

The simplest fix is to proactively make your input field resign first responder as soon as the user starts scrolling down (which triggers keyboard dismissal). Here's how to implement it:

1. Add a scroll view delegate to your ChatViewController (since UITableView inherits from UIScrollView):

extension ChatViewController: UIScrollViewDelegate {
    func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
        // Only act if the keyboard is visible and the input field is active
        if isKeyboardVisible, messageInputView.yourTextField.isFirstResponder {
            messageInputView.yourTextField.resignFirstResponder()
        }
    }
}

2. Track keyboard visibility with notifications (add this setup in viewDidLoad()):

private var isKeyboardVisible = false

override func viewDidLoad() {
    super.viewDidLoad()
    tableView.keyboardDismissMode = .interactive
    tableView.delegate = self // Don't forget to set the delegate!
    
    // Register keyboard state notifications
    NotificationCenter.default.addObserver(
        self,
        selector: #selector(keyboardWillShow),
        name: UIResponder.keyboardWillShowNotification,
        object: nil
    )
    NotificationCenter.default.addObserver(
        self,
        selector: #selector(keyboardWillHide),
        name: UIResponder.keyboardWillHideNotification,
        object: nil
    )
}

@objc private func keyboardWillShow() {
    isKeyboardVisible = true
}

@objc private func keyboardWillHide() {
    isKeyboardVisible = false
}

Solution 2: Override resignFirstResponder in Your Input Accessory View #

Sometimes the warning comes from the input accessory view itself being asked to resign. Fix this by ensuring your custom messageInputView handles the resign properly:

class MessageInputView: UIView {
    @IBOutlet weak var yourTextField: UITextField!
    
    override func resignFirstResponder() -> Bool {
        // First make sure the text field resigns its status
        yourTextField.resignFirstResponder()
        // Then let the superclass handle its own resign logic
        return super.resignFirstResponder()
    }
}

Solution 3: Ensure Your View Controller is the Proper First Responder #

When using a custom inputAccessoryView, your view controller must return true for canBecomeFirstResponder—this is a common oversight that causes weird first responder issues. Add this to your ChatViewController:

override var canBecomeFirstResponder: Bool {
    return true
}

override func viewDidLoad() {
    super.viewDidLoad()
    // Prevent the table view from trying to become first responder
    tableView.canBecomeFirstResponder = false
}

Bonus: Pinpoint the Exculprit #

If you're still stuck, add debug logs or breakpoints in the resignFirstResponder methods of your input field and table view. This will let you see exactly which view is rejecting the resign request, helping you narrow down the exact issue.

内容的提问来源于stack exchange，提问作者Mikael