当用户选择底部文本字段时， View 中的所有元素都会向上移动键盘的高度，直到用户关闭键盘。

问题发生在用户选择底部文本字段之后。最初元素都正确向上移动。但是，当用户键入第一个字符时，所有元素都会向下移动到原始位置。结果，用户无法再看到他们正在编辑的文本字段。一旦用户关闭键盘，他们就会看到元素上升到它们应该在的位置，然后又回到原来的位置。

我已经缩小了导致问题的范围，但我不明白为什么会这样。我的项目可以在 GitHub 上找到 https://github.com/JMNolan/memesicle

我对 Swift 还是很陌生，对一般的编码也很陌生，所以非常感谢所有帮助。对于不想使用 GitHub 的任何人，我还在下面包含了与此过程相关的代码片段

这就是将元素向上移动到键盘高度的原因

//moves the view up when the keyboard appears to keep the text field 
visible
    @objc func keyboardWillShow (notification: NSNotification){
        if bottomTextFieldActive == true{
            keyboardHeight = getKeyboardHeight(notification: 
notification)
            imagePickerView.frame.origin.y -= keyboardHeight
            topText.frame.origin.y -= keyboardHeight
            bottomText.frame.origin.y -= keyboardHeight
            toolbar.frame.origin.y -= keyboardHeight
        }
    }

这就是当键盘关闭时将元素移回键盘高度的原因

//moves the view down when the keyboard is dismissed to show the full view again
@objc func keyboardWillHide (notification: NSNotification){
    imagePickerView.frame.origin.y += keyboardHeight
    topText.frame.origin.y += keyboardHeight
    bottomText.frame.origin.y += keyboardHeight
    toolbar.frame.origin.y += keyboardHeight
    //shareButton.frame.origin.y += keyboardHeight
    print("keyboard just hid")
}

这就是调用上面的函数

func subscribeToKeyboardNotifications(){
        NotificationCenter.default.addObserver(self, selector: 
#selector(keyboardWillShow), name: 
NSNotification.Name.UIKeyboardWillShow, object: nil)

        NotificationCenter.default.addObserver(self, selector: 
 #selector(keyboardWillHide), name: 
NSNotification.Name.UIKeyboardWillHide, object: nil)
    }

这就是我在将元素上下移动键盘高度时使用的 keyboardHeight 的方式。

//get the height of the keyboard to determine how far up to move the view when editing the bottom text field
func getKeyboardHeight(notification: NSNotification) -> CGFloat {
    let userinfo = notification.userInfo
    let keyboardSize = userinfo![UIKeyboardFrameEndUserInfoKey] as!NSValue
    return keyboardSize.cgRectValue.height
}

最佳答案

当您在 UITextField 中键入时，您的屏幕元素跳来跳去的原因是您的 View 限制。当您向 View 添加约束时，您有点丧失了稍后通过​​更改其框架来移动 subview 的能力 - 每次 View 重新计算其 subview 的位置时，它将返回使用约束提供的原始值并忽略您所做的框架更改。

因为你有几个不同的屏幕元素要移动，解决这个问题的最简单方法是将所有 subview (文本字段、 ImageView 等)放在 UIScrollView 中，并且然后在键盘出现时调整 ScrollView 的内容插入属性。这将完全替换您更改帧大小的代码。 Apple has a help document about how to do this ，但重要的部分如下:

Adjusting your content typically involves temporarily resizing one or more views and positioning them so that the text object remains visible. The simplest way to manage text objects with the keyboard is to embed them inside a UIScrollView object or one of its subclasses, like UITableView. Note that UITableViewController automatically resizes and repositions its table view when there is inline editing of text fields (to learn more, see View Controllers and Navigation-Based Apps).

When the keyboard is displayed, all you have to do is reset the content area of the scroll view and scroll the desired text object into position. Thus, in response to a UIKeyboardDidShowNotification, your handler method would do the following:

1. Get the size of the keyboard.

2. Adjust the bottom content inset of your scroll view by the keyboard height.

3. Scroll the target text field into view.

// Called when the UIKeyboardDidShowNotification is sent.
- (void)keyboardWasShown:(NSNotification*)aNotification
{
    NSDictionary* info = [aNotification userInfo];
    CGSize kbSize = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;

    UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, kbSize.height, 0.0);
    scrollView.contentInset = contentInsets;
    scrollView.scrollIndicatorInsets = contentInsets;

    // If active text field is hidden by keyboard, scroll it so it's visible
    // Your app might not need or want this behavior.
    CGRect aRect = self.view.frame;
    aRect.size.height -= kbSize.height;
    if (!CGRectContainsPoint(aRect, activeField.frame.origin) ) {
        [self.scrollView scrollRectToVisible:activeField.frame animated:YES];
    }
}

// Called when the UIKeyboardWillHideNotification is sent
- (void)keyboardWillBeHidden:(NSNotification*)aNotification
{
    UIEdgeInsets contentInsets = UIEdgeInsetsZero;
    scrollView.contentInset = contentInsets;
    scrollView.scrollIndicatorInsets = contentInsets;
}

关于swift - 在文本字段中键入字符时 UI 元素移动，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/48393580/