自定义键盘UIButton响应迟缓，如何优化提升响应速度？

Hey there, let's tackle this keyboard responsiveness issue you're facing—those one-star reviews are no fun, so let's get your buttons feeling snappier right away!

First, let's address the core problem you noted: UIControlEventTouchUpInside waits for the user to lift their finger, which feels laggy for fast typists. Switching to UIControlEventTouchDown is the right first step, but we need to handle edge cases to avoid frustrating users further. Here's how to implement this properly:

1. Switch to touchDown for Instant Triggering #

Bind your button actions to the touchDown event instead of touchUpInside. This fires the moment the user's finger makes contact with the button, cutting out the "wait for lift" delay entirely.

Objective-C Example: #

[yourKeyboardButton addTarget:self 
                       action:@selector(buttonTapped:) 
             forControlEvents:UIControlEventTouchDown];

Swift Example: #

yourKeyboardButton.addTarget(self, action: #selector(buttonTapped(_:)), for: .touchDown)

2. Handle Mis-Taps with Additional Events #

The downside of touchDown is that if a user starts touching a button but slides their finger away (intending to tap another key), the action will still have fired. Fix this by listening for touchDragExit and touchCancel events to undo the action:

Objective-C: #

[yourKeyboardButton addTarget:self 
                       action:@selector(buttonCancelled:) 
             forControlEvents:UIControlEventTouchDragExit | UIControlEventTouchCancel];

Swift: #

yourKeyboardButton.addTarget(self, action: #selector(buttonCancelled(_:)), for: [.touchDragExit, .touchCancel])

In the buttonCancelled: method, reverse the input from the initial tap (e.g., delete the character that was just added to the text field).

3. Expand Button Hit Areas (Optional but Helpful) #

Sometimes "slow response" is actually users missing the button entirely without realizing it. Expand the tap target of your buttons to make them easier to hit, even if the visual size stays the same. Override pointInside:withEvent: in your custom UIButton subclass:

Objective-C: #

- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event {
    // Expand bounds by 10pt on all sides—adjust this value as needed
    CGRect expandedBounds = CGRectInset(self.bounds, -10, -10);
    return CGRectContainsPoint(expandedBounds, point);
}

Swift: #

override func point(inside point: CGPoint, with event: UIEvent?) -> Bool {
    let expandedBounds = bounds.insetBy(dx: -10, dy: -10)
    return expandedBounds.contains(point)
}

4. Eliminate Main Thread Blocking #

Even with fast event triggering, if your main thread is tied up with heavy work (like complex calculations or synchronous network calls), the UI will feel laggy. Make sure all non-UI work happens on background threads. For example, if you're processing input before sending it to the text field, dispatch that work to a background queue:

Objective-C: #

- (void)buttonTapped:(UIButton *)sender {
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        // Do heavy processing here
        NSString *processedInput = [self processInput:sender.titleLabel.text];
        
        dispatch_async(dispatch_get_main_queue(), ^{
            // Update UI or send input to text field on main thread
            [self insertTextIntoActiveField:processedInput];
        });
    });
}

Swift: #

@objc func buttonTapped(_ sender: UIButton) {
    DispatchQueue.global().async {
        let processedInput = self.processInput(sender.titleLabel?.text ?? "")
        
        DispatchQueue.main.async {
            self.insertTextIntoActiveField(processedInput)
        }
    }
}

5. Add Immediate Visual Feedback #

Users rely on visual cues to know a button has been triggered. Make sure your button changes state instantly when touchDown fires—for example, shrink the button slightly, darken its color, or add a shadow. This reinforces that the tap was registered immediately, even if the text appears instantly.

By combining these steps, you'll make your keyboard feel significantly more responsive to fast typists, which should help turn those one-star reviews around.

内容的提问来源于stack exchange，提问作者user9373173