ios - 存在键盘时快速向上移动 ScrollView

Question

我正在开发一个 iOS 应用程序，目前我的所有元素都在 ScrollView 中，当键盘出现时，我将 View 向上移动 250 磅。这解决了我的问题，但每个设备的键盘大小始终不同。

如何检测我的文本字段离屏幕底部有多远以及键盘有多高？

Answer 1

您应该观察显示和隐藏键盘的通知。之后，您可以获得准确的键盘大小，并移动或更改 ScrollView 的内容插图。这是示例代码:

extension UIViewController {
    func registerForKeyboardDidShowNotification(scrollView: UIScrollView, usingBlock block: (NSNotification -> Void)? = nil) {
        NSNotificationCenter.defaultCenter().addObserverForName(UIKeyboardDidShowNotification, object: nil, queue: nil, usingBlock: { (notification) -> Void in
            let userInfo = notification.userInfo!
            let keyboardSize = userInfo[UIKeyboardFrameBeginUserInfoKey]?.CGRectValue.size
            let contentInsets = UIEdgeInsetsMake(scrollView.contentInset.top, scrollView.contentInset.left, keyboardSize!.height, scrollView.contentInset.right)

            scrollView.scrollEnabled = true
            scrollView.setContentInsetAndScrollIndicatorInsets(contentInsets)
            block?(notification)
        })
    }

    func registerForKeyboardWillHideNotification(scrollView: UIScrollView, usingBlock block: (NSNotification -> Void)? = nil) {
        NSNotificationCenter.defaultCenter().addObserverForName(UIKeyboardWillHideNotification, object: nil, queue: nil, usingBlock: { (notification) -> Void in
            let contentInsets = UIEdgeInsetsMake(scrollView.contentInset.top, scrollView.contentInset.left, 0, scrollView.contentInset.right)
            scrollView.setContentInsetAndScrollIndicatorInsets(contentInsets)
            scrollView.scrollEnabled = false
            block?(notification)
        })
    }
}

extension UIScrollView {
    func setContentInsetAndScrollIndicatorInsets(edgeInsets: UIEdgeInsets) {
        self.contentInset = edgeInsets
        self.scrollIndicatorInsets = edgeInsets
    }
}

在您要移动 ScrollView 的 UIViewController 中，只需在 viewDidLoad() 函数下添加下一行

override func viewDidLoad() {
    super.viewDidLoad()

    registerForKeyboardDidShowNotification(scrollView)
    registerForKeyboardWillHideNotification(scrollView)
}