我创建了一个模因生成器应用程序来更好地学习 Swift 和 Xcode。我正在学习当用户与会被键盘阻挡的文本字段交互时移动视图。我有这个功能,但有一个例外。所需的功能是当用户为底部文本字段输入文本时让视图向上滑动,bot 顶部。无论用户正在与之交互的文本字段如何,视图都会向上滑动。
如何将此功能仅分配给底部文本字段?这是我的源代码:
import UIKit
class ViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate, UITextFieldDelegate {
@IBOutlet weak var imagePickerView: UIImageView!
@IBOutlet weak var cameraButton: UIBarButtonItem!
@IBOutlet weak var topText: UITextField!
@IBOutlet weak var bottomText: UITextField!
let memeTextAttributes:[String:Any] = [
NSAttributedStringKey.strokeColor.rawValue: UIColor.black,
NSAttributedStringKey.foregroundColor.rawValue: UIColor.white,
NSAttributedStringKey.font.rawValue: UIFont(name: "HelveticaNeue-CondensedBlack", size: 30)!,
NSAttributedStringKey.strokeWidth.rawValue: -5.0]
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
subscribeToKeyboardNotifications()
}
override func viewDidLoad() {
super.viewDidLoad()
// Diable camer a button if camera ource isn't available
cameraButton.isEnabled = UIImagePickerController.isSourceTypeAvailable(.camera)
topText.delegate = self
bottomText.delegate = self
topText.textAlignment = .center
bottomText.textAlignment = .center
topText.defaultTextAttributes = memeTextAttributes
bottomText.defaultTextAttributes = memeTextAttributes
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
unsubscribeFromKeyboardNotifications()
}
// MARK: Delegate Methods
func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
if let image = info[UIImagePickerControllerOriginalImage] as? UIImage {
imagePickerView.image = image
self.dismiss(animated: true, completion: nil)
}
}
func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
self.dismiss(animated: true, completion: nil)
}
func textFieldDidBeginEditing(_ textField: UITextField) {
textField.text = ""
}
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
self.topText.resignFirstResponder()
self.bottomText.resignFirstResponder()
return true
}
// MARK: Move the keyboard up when the bottom textfield is tapped
@objc func keyboardWillShow(_ notification:Notification) {
view.frame.origin.y = 0 - getKeyboardHeight(notification)
}
func getKeyboardHeight(_ notification:Notification) -> CGFloat {
let userInfo = notification.userInfo
let keyboardSize = userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue // of CGRect
return keyboardSize.cgRectValue.height
}
func subscribeToKeyboardNotifications() {
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(_:)), name: .UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(_:)), name: .UIKeyboardWillHide, object: nil)
}
func unsubscribeFromKeyboardNotifications() {
NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillShow, object: nil)
NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillHide, object: nil)
}
// MARK: Move view down when keyboard is dismissed
@objc func keyboardWillHide(_ notification: Notification) {
view.frame.origin.y = 0
}
// MARK: IBActions
@IBAction func pickAnImageFromAlbum(_ sender: Any) {
let pickerController = UIImagePickerController()
pickerController.delegate = self
pickerController.sourceType = .photoLibrary
present(pickerController, animated: true, completion: nil)
}
@IBAction func pickAnImageFromCamera(_ sender: Any) {
let imagePicker = UIImagePickerController()
imagePicker.delegate = self
imagePicker.sourceType = .camera
present(imagePicker, animated: true, completion: nil)
}
}