馆藏视图高度

Question

我正在使用高度限制来降低键盘弹出时集合视图的高度。

@objc func keyboardWillShow(notification: NSNotification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
    self.collectionViewHeightConstraint.constant = 250 - keyboardSize.height/2
        self.addButtonConstraint.constant = keyboardSize.height+20

    }
}

@objc func keyboardWillHide(notification: NSNotification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
    self.collectionViewHeightConstraint.constant = 250
    self.addButtonConstraint.constant = 20

      }
}

如何使集合视图显示的是上半部而不是后半部？

Answer 1

尝试在keyboardWillShow方法中调用它：

collectionView.scrollToTop(false)

扩展名

extension UIScrollView {
    func scrollToTop(_ animated: Bool) {
        var topContentOffset: CGPoint
        if #available(iOS 11.0, *) {
            topContentOffset = CGPoint(x: -safeAreaInsets.left, y: -safeAreaInsets.top)
        } else {
            topContentOffset = CGPoint(x: -contentInset.left, y: -contentInset.top)
        }
        setContentOffset(topContentOffset, animated: animated)
    }
}