我认为如果您使用Swift，最好的方法是使用面向协议的编程。
首先，您必须创建KeyboardCapable协议，使符合该协议的任何UIViewController都能够注册和注销键盘观察员：
import Foundation
import UIKit
protocol KeyboardCapable: KeyboardAnimatable {
func keyboardWillShow(notification: NSNotification)
func keyboardWillHide(notification: NSNotification)
}
extension KeyboardCapable where Self: UIViewController {
func registerKeyboardNotifications() {
NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillShow:"), name:UIKeyboardWillShowNotification, object: nil)
NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillHide:"), name:UIKeyboardWillHideNotification, object: nil)
}
func unregisterKeyboardNotifications() {
NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillShowNotification, object: nil)
NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillHideNotification, object: nil)
}
}
您已经注意到上述代码中有一个无关的KeyboardAnimatable关键字。这只是我们需要创建的下一个协议的名称：
import Foundation
import UIKit
protocol KeyboardAnimatable {
}
extension KeyboardAnimatable where Self: UIViewController {
func performKeyboardShowFullViewAnimation(withKeyboardHeight height: CGFloat, andDuration duration: NSTimeInterval) {
UIView.animateWithDuration(duration, animations: { () -> Void in
self.view.frame = CGRectMake(view.frame.origin.x, -height, view.bounds.width, view.bounds.height)
}, completion: nil)
}
func performKeyboardHideFullViewAnimation(withDuration duration: NSTimeInterval) {
UIView.animateWithDuration(duration, animations: { () -> Void in
self.view.frame = CGRectMake(view.frame.origin.x, 0.0, view.bounds.width, view.bounds.height)
}, completion: nil)
}
}
这个KeyboardAnimatable协议为所有符合它的UIViewController提供了两种方法，分别为整个视图上下设置动画。
好的，如果KeyboardCapable符合KeyboardAnimatable，则所有符合Keyboard Capable的UIViewController也符合KeyboaardAnimatable。这很酷。
让我们看看符合KeyboardCapable的UIViewController，并对键盘事件做出反应：
import Foundation
import UIKit
class TransferConfirmViewController: UIViewController, KeyboardCapable {
//MARK: - LIFE CYCLE
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
registerKeyboardNotifications()
}
override func viewWillDisappear(animated: Bool) {
super.viewWillDisappear(animated)
unregisterKeyboardNotifications()
}
//MARK: - NOTIFICATIONS
//MARK: Keyboard
func keyboardWillShow(notification: NSNotification) {
let keyboardHeight = (notification.userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue).CGRectValue().height
let animationDuration = notification.userInfo![UIKeyboardAnimationDurationUserInfoKey] as! Double
performKeyboardShowFullViewAnimation(withKeyboardHeight: keyboardHeight, andDuration: animationDuration)
}
func keyboardWillHide(notification: NSNotification) {
let animationDuration = notification.userInfo![UIKeyboardAnimationDurationUserInfoKey] as! Double
performKeyboardHideFullViewAnimation(withDuration: animationDuration)
}
}
现在，您的UIViewController将响应键盘事件，并将因此产生动画效果。
注意：如果您想要自定义动画而不是推拉视图，则必须在KeyboardAnimatable协议上定义自定义方法或在Keyboard功能上执行这些方法。这取决于你。
