更改鍵盤通知上的視圖布局（Swift，iOS）

Question

我正在嘗試使用Swift為iOS應用創建登錄屏幕。

這是我希望隱藏鍵盤后的外觀。 用戶點擊一個文本字段后，我想更改為如下所示 ，並顯示鍵盤。 如您所見，它更緊湊

我嘗試自己做，但是似乎無法使用在網上找到的示例來弄清楚，因為我在InterfaceBuilder使用AutoLayoutConstraints 。 一切都嵌入到UIScrollView 。

我的問題是，我這樣做正確嗎？ 就像在其中一樣，刪除先前在InterfaceBuilder設置的所有約束，然后以編程方式重做它們以使其看起來像我想要的。

有一個更好的方法嗎？ 這似乎很乏味。 我是Swift / iOS編程的新手，因此很抱歉這是我的道歉。

到目前為止，這是我所做的：

---

@IBOutlet weak var scrollView: UIScrollView!
@IBOutlet weak var logoImage: UIImageView!
@IBOutlet weak var logoText: UILabel!
@IBOutlet weak var usernameTextField: UITextField!
@IBOutlet weak var passwordTextField: UITextField!
@IBOutlet weak var loginButton: UIButton!
@IBOutlet weak var forgotPasswordButton: UIButton!
@IBOutlet weak var createAccountButton: UIButton!

override func viewDidLoad() {
  super.viewDidLoad()
  registerForKeyboardNotifications()
}

---

func registerForKeyboardNotifications() {
        let notificationCenter = NSNotificationCenter.defaultCenter()
        notificationCenter.addObserver(self, selector: "keyboardWillBeShown:", name: UIKeyboardWillShowNotification, object: nil)
        notificationCenter.addObserver(self, selector: "keyboardWillBeHidden:", name: UIKeyboardWillHideNotification, object: nil)
}

---

func keyboardWillBeShown(sender: NSNotification) {
    let userInfo = sender.userInfo!
    let keyboardHeight = (userInfo[UIKeyboardFrameEndUserInfoKey] as! NSValue).CGRectValue().height

    let screenSize: CGRect = UIScreen.mainScreen().bounds           // get screen size
    let screenWidth = screenSize.width                              // ... screen width
    let screenHeight = screenSize.height                            // ... screen height
    let heightToFit = screenHeight - keyboardHeight                 // ... height of screen with keyboard

    self.view.translatesAutoresizingMaskIntoConstraints = false

    self.view.removeConstraints(self.view.constraints)

    self.view.addConstraint(
    NSLayoutConstraint(item: self.scrollView,
                  attribute: .Bottom,
                  relatedBy: .Equal,
                     toItem: self.view,
                  attribute: .Bottom,
                 multiplier: 1.0,
                   constant: -keyboardHeight ))

    self.view.addConstraint(
    NSLayoutConstraint(item: self.scrollView,
                  attribute: .Top,
                  relatedBy: .Equal,
                     toItem: self.view,
                  attribute: .Top,
                 multiplier: 1.0,
                   constant: 0.0))


    self.view.addConstraint(
    NSLayoutConstraint(item: self.scrollView,
                  attribute: .Trailing,
                  relatedBy: .Equal,
                     toItem: self.view,
                  attribute: .Trailing,
                 multiplier: 1.0,
                   constant: 0.0))

    self.view.addConstraint(
    NSLayoutConstraint(item: self.scrollView,
                  attribute: .Leading,
                  relatedBy: .Equal,
                     toItem: self.view,
                  attribute: .Leading,
                 multiplier: 1.0,
                   constant: 0.0))

    self.view.addConstraint(
    NSLayoutConstraint(item: self.scrollView,
                  attribute: .Height,
                  relatedBy: .Equal,
                     toItem: nil,
                  attribute: .NotAnAttribute,
                 multiplier: 1.0,
                   constant: heightToFit))

    self.view.addConstraint(
    NSLayoutConstraint(item: self.view,
                  attribute: .Width,
                  relatedBy: .Equal,
                     toItem: nil,
                  attribute: .NotAnAttribute,
                 multiplier: 1.0,
                   constant: screenWidth))


    self.scrollView.setContentOffset(CGPointMake(0, self.usernameTextField.frame.origin.y - 50), animated: true)
}

---

func keyboardWillBeHidden(sender: NSNotification) {
        let screenSize: CGRect = UIScreen.mainScreen().bounds           // get screen size
        let screenWidth = screenSize.width                              // ... screen width
        let screenHeight = screenSize.height                            // ... screen height

        self.view.translatesAutoresizingMaskIntoConstraints = true

        self.view.removeConstraints(self.view.constraints)

        self.view.addConstraint(
            NSLayoutConstraint(item: self.scrollView,
                          attribute: .Bottom,
                          relatedBy: .Equal,
                             toItem: self.view,
                          attribute: .Bottom,
                         multiplier: 1.0,
                           constant: screenHeight ))

        self.view.addConstraint(
            NSLayoutConstraint(item: self.scrollView,
                          attribute: .Top,
                          relatedBy: .Equal,
                             toItem: self.view,
                          attribute: .Top,
                        multiplier: 1.0,
                          constant: 0.0))

        self.view.addConstraint(
            NSLayoutConstraint(item: self.scrollView,
                          attribute: .Trailing,
                          relatedBy: .Equal,
                             toItem: self.view,
                          attribute: .Trailing,
                         multiplier: 1.0,
                           constant: 0.0))

        self.view.addConstraint(
            NSLayoutConstraint(item: self.scrollView,
                          attribute: .Leading,
                          relatedBy: .Equal,
                             toItem: self.view,
                          attribute: .Leading,
                         multiplier: 1.0,
                           constant: 0.0))

        self.view.addConstraint(
            NSLayoutConstraint(item: self.scrollView,
                          attribute: .Height,
                          relatedBy: .Equal,
                             toItem: nil,
                          attribute: .NotAnAttribute,
                        multiplier: 1.0,
                          constant: screenHeight))

        self.view.addConstraint(
            NSLayoutConstraint(item: self.view,
                          attribute: .Width,
                          relatedBy: .Equal,
                             toItem: nil,
                          attribute: .NotAnAttribute,
                         multiplier: 1.0,
                           constant: screenWidth))


  self.scrollView.setContentOffset(CGPointMake(0, -self.usernameTextField.frame.origin.y + 50), animated: true)
}

Answer 1

不幸的是，我無法使其與AutoLayoutConstraints ，因此我禁用了它並自己進行了所有數學運算。

這是一個小片段：

let screenSize: CGRect = UIScreen.mainScreen().bounds           // get screen size
let screenWidth = screenSize.width                              // ... screen width
let screenHeight = screenSize.height                            // ... screen height
let padding: CGFloat = 30                                       // space on left and right
let adjustedViewWidth = screenWidth - 2*padding

self.scrollView.frame = CGRectMake(0, 0, screenWidth, screenHeight)

self.logoImage.frame = CGRectMake(screenWidth/2 - self.logoImage.frame.width/2, self.logoImage.frame.origin.y, self.logoImage.frame.width, self.logoImage.frame.height)
self.logoText.frame = CGRectMake(screenWidth/2 - self.logoText.frame.width/2, self.logoText.frame.origin.y, self.logoText.frame.width, self.logoText.frame.height)
self.usernameTextField.frame = CGRectMake(screenWidth/2 - adjustedViewWidth/2, self.usernameTextField.frame.origin.y, adjustedViewWidth, self.usernameTextField.frame.height)
self.passwordTextField.frame = CGRectMake(screenWidth/2 - adjustedViewWidth/2, self.passwordTextField.frame.origin.y, adjustedViewWidth, self.passwordTextField.frame.height)
self.loginButton.frame = CGRectMake(screenWidth/2 - adjustedViewWidth/2, self.loginButton.frame.origin.y, adjustedViewWidth, self.loginButton.frame.height)