更改键盘通知上的视图布局（Swift、iOS）
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【中文标题】更改键盘通知上的视图布局（Swift、iOS）【英文标题】：Change View Layout on Keyboard Notifications (Swift, iOS) 【发布时间】：2016-03-23 17:36:25 【问题描述】：我正在尝试使用 Swift 为 ios 应用创建登录屏幕。
Here 是我希望它在没有隐藏键盘的情况下的样子。一旦用户点击文本字段，我想更改为看起来像this，并显示键盘。如您所见，它更紧凑
我尝试过自己做，但使用我在网上找到的示例似乎无法弄清楚，因为我在InterfaceBuilder 中使用AutoLayoutConstraints。一切都嵌入到UIScrollView。
我的问题是，我这样做是否正确？例如，删除之前在 InterfaceBuilder 中设置的所有约束，然后以编程方式重做它们以使其看起来像我想要的那样。
有没有更好的方法来做到这一点？这似乎很乏味。我是 Swift/iOS 编程的新手，所以如果这是一个明显的问题，我深表歉意。
到目前为止，这是我所做的：
@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)
【问题讨论】：
您的部署目标是什么？ iOS 9 还是更早的版本？ 【参考方案1】：不幸的是，我无法让它与AutoLayoutConstraints 一起工作，所以我禁用了它并自己完成了所有数学运算。
这是一个小sn-p：
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)
【讨论】：
嗨@aashah7，您不需要添加或删除约束，您可以使用视图之间的乘数（UIImage、UILabel、UITextfield 和 UIButton）来实现所需的输出购买。并在键盘打开时更改滚动视图的高度约束。确保图像视图的约束连接到滚动视图的顶部，并且忘记密码连接到滚动视图的底部以上是关于更改键盘通知上的视图布局（Swift、iOS）的主要内容，如果未能解决你的问题，请参考以下文章