Handling UITextField Visibility with Keyboard Appearance in iOS

When developing an iOS application, a common user interface challenge involves managing text fields within forms or input screens. Specifically, when a keyboard appears for editing a UITextField, it can obscure other UI elements, including the text field itself if positioned towards the bottom of the screen. To enhance user experience, the view should adjust to ensure that active text fields remain visible and accessible. This tutorial explores how to achieve this behavior using UIScrollView in iOS.

Understanding the Problem

When users tap on a UITextField near the bottom of an interface, the keyboard may cover it due to its size. This issue is particularly prevalent on devices with smaller screens or when multiple text fields are stacked vertically. Simply presenting a scrolling view won’t automatically adjust the position of the content; hence manual intervention is necessary.

Using UIScrollView for Scrolling

UIScrollView serves as a container allowing users to scroll through content that exceeds the visible bounds of its frame. For managing keyboard visibility, we will use UIScrollView in conjunction with NotificationCenter to listen for keyboard appearance and disappearance events.

Step 1: Setting Up the ScrollView

To start, ensure your view hierarchy includes a UIScrollView containing the UITextFields:

• Add a UIScrollView: Place it as a container around your text fields. This scroll view should be larger than its frame if you want scrolling to occur.

• Configure Content Size: Set the contentSize of the UIScrollView to accommodate all contained elements, ensuring that it exceeds the visible portion.

scrollView.contentSize = CGSize(width: scrollView.frame.size.width, height: totalHeight)

Step 2: Handling Keyboard Notifications

Listen for keyboard events using NotificationCenter. Register observers in your view controller’s viewDidLoad method:

• Add Observers: Listen to UIKeyboardWillShowNotification and UIKeyboardWillHideNotification.

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(_:)), name: UIResponder.keyboardWillShowNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(_:)), name: UIResponder.keyboardWillHideNotification, object: nil)

• Implement Handlers: Define methods to adjust the view when these notifications are triggered.

@objc func keyboardWillShow(_ notification: Notification) {
    if let keyboardFrame = notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect {
        let keyboardHeight = keyboardFrame.height

        // Adjust ScrollView's content inset and scroll indicator insets
        scrollView.contentInset.bottom += keyboardHeight
        scrollView.scrollIndicatorInsets.bottom += keyboardHeight
        
        // Optionally, scroll to active text field if needed
        if let activeTextField = view.findFirstResponder() as? UITextField {
            let textFieldBottomY = activeTextField.convert(activeTextField.bounds, to: view).maxY
            let scrollViewVisibleRect = CGRect(x: 0, y: scrollView.contentOffset.y, width: scrollView.frame.width, height: scrollView.contentSize.height - scrollView.contentOffset.y)

            if !scrollViewVisibleRect.contains(CGPoint(x: activeTextField.center.x, y: textFieldBottomY)) {
                scrollView.scrollRectToVisible(activeTextField.bounds, animated: true)
            }
        }
    }
}

@objc func keyboardWillHide(_ notification: Notification) {
    scrollView.contentInset.bottom = 0
    scrollView.scrollIndicatorInsets.bottom = 0
}

Step 3: Adjusting View on Keyboard Appearance

Modify your view’s frame to ensure the active text field remains visible. This involves calculating the offset needed based on the keyboard’s height and current scroll position.

• Find Active TextField: Implement a method to find the currently focused UITextField.

extension UIView {
    func findFirstResponder() -> UIResponder? {
        if self.isFirstResponder { return self }
        for subview in self.subviews {
            if let firstResponder = subview.findFirstResponder() {
                return firstResponder
            }
        }
        return nil
    }
}

Step 4: Clean Up

Ensure you remove observers when the view controller is deallocated to prevent memory leaks.

deinit {
    NotificationCenter.default.removeObserver(self)
}

Conclusion

By integrating UIScrollView with keyboard event handling, developers can ensure that text fields remain visible and accessible even when a keyboard appears on-screen. This approach not only enhances usability but also contributes to a seamless user experience in iOS applications. Remember to test across different devices to account for varying screen sizes and keyboard dimensions.