仅在隐藏文本字段时使用键盘移动视图

Question

我正试图让我的应用程序在键盘出现时移动视图，到目前为止，结果...至少可以说是混杂的。我可以让它移动，问题是它要么是硬编码的，要么只能部分工作。

我的视图中有多个文本字段，当我点击它们时，有时取决于我的滚动位置，它会被键盘隐藏。

现在我需要我的应用程序做的是仅当活动文本字段被键盘隐藏时才移动视图以查看文本字段。

我的视图层次结构如下：

所以我有一个滚动视图，在滚动视图中我有一个名为 ContentView 的 UIView，在 ContentView 中我有我所有的文本字段和标签。

问题是，我无法对其进行硬编码，因为我的应用程序是通用的，只有当它隐藏文本字段时，我才需要让键盘移动视图。因为在用户使用 iPad 的情况下，视图可能永远不必移动

我使用了以下堆栈溢出答案但没有结果：

Swift: Scroll View only when a TextField or Button is hidden by the Keyboard

Move view with keyboard using Swift

这是我的代码，实际上来自这些答案之一：

override func viewDidLoad() {
    super.viewDidLoad()

    NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(NewPaxController.keyboardWillShow), name: UIKeyboardWillShowNotification, object: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(NewPaxController.keyboardWillHide), name: UIKeyboardWillHideNotification, object: nil)

}



func keyboardWillShow(notification:NSNotification) {
    if keyboardIsPresent == false {
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {
            self.ContentView.frame.origin.y -= keyboardSize.height
            keyboardIsPresent = true
        }
    }
}

func keyboardWillHide(notification:NSNotification) {
    if keyboardIsPresent == true {
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {
            self.ContentView.frame.origin.y += keyboardSize.height
            keyboardIsPresent = false
        }
    }
}

我几乎 100% 确定我所有的错误都来自我有一个 ContentView 的事实......但在我的情况下我需要它。提前感谢您的帮助

Answer 1

这是它的代码，很简单，但如果你仍然需要帮助，我会进一步解释。

#pragma mark - Keyboard Observer events

-(void)keyboardWillShow:(NSNotification*)notification {

    NSDictionary *info = [notification userInfo];
    CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
    keyboardHeight = kbSize.height;
    [self updateScrollViewPosition];
}

-(void)keyboardDidChange:(NSNotification *)notification {

    NSDictionary *info = [notification userInfo];
    CGSize kbSizeBegin = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
    CGSize kbSizeEnd = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;
    if (kbSizeBegin.height != kbSizeEnd.height) {
        keyboardHeight = kbSizeEnd.height;
        if (activeTextField && [activeTextField isFirstResponder]) {
            [self updateScrollViewPosition];
        }
    }
}

-(void)keyboardWillHide:(NSNotification*)notification {

    keyboardHeight = 0;
    activeTextField = nil;
    [self resignAllTextFields];
}

#pragma mark - UITextFieldDelegate Methods

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField {
    activeTextField = textField;
    return YES;
}

- (void)textFieldDidBeginEditing:(UITextField *)textField {

    activeTextField = textField;
    [self updateScrollViewPosition];
}

- (BOOL)textFieldShouldReturn:(UITextField *)textField {

    keyboardHeight = 0;
    activeTextField = nil;
    [textField resignFirstResponder];
    return YES;
}

#pragma mark - Update Method

-(void)updateScrollViewPosition {

    if (keyboardHeight > 0 && activeTextField) {
        CGRect frame = activeTextField.frame;
        CGFloat yPoint = scrollView.frame.origin.y+frame.origin.y+frame.size.height+8.0;
        CGFloat height = self.view.frame.size.height-keyboardHeight;
        CGFloat diff = yPoint-height;
        if (diff > 0.0) {
            [scrollView setContentOffset:CGPointMake(0, diff) animated:YES];
        }
        else {
            CGFloat diff = scrollView.contentSize.height-scrollView.contentOffset.y;
            if (diff<scrollView.frame.size.height) {
                diff = scrollView.contentSize.height-scrollView.frame.size.height;
                if (diff < 0) {
                    diff = 0.0;
                }
                [scrollView setContentOffset:CGPointMake(0, diff) animated:YES];
            }
        }
    }
    else {
        CGFloat diff = scrollView.contentSize.height-scrollView.contentOffset.y;
        if (diff<scrollView.frame.size.height) {
            diff = scrollView.contentSize.height-scrollView.frame.size.height;
            if (diff < 0) {
                diff = 0.0;
            }
            [scrollView setContentOffset:CGPointMake(0, diff) animated:YES];
        }
    }
}

#pragma mark

编辑：根据要求提供一个简单的resignAllTextFields 方法。 containerView 是包含所有UITextField 的视图。

-(void)resignAllTextFields {

    for (UIView *view in containerView.subviews) {
        if ([view isKindOfClass:[UITextField class]]) {
            UITextField *textField = (UITextField*)view;
            [textField resignFirstResponder];
        }
    }
    [self updateScrollViewPosition];
}

Answer 2

当键盘出现时，您不应该修改框架。

相反，您需要将滚动视图scrollView.contentInset.bottom 的底部插入从零设置为键盘高度。当键盘消失时，您将 inset 设置回零。

这整个问题只需要 10 行代码就可以解决。

字面上从通知中获取键盘高度，在显示 KB 时将其存储在类中的局部变量中，并使用该值在委托回调/事件处理程序方法中设置插入。

这里的诀窍是，设置非零插图将有效地将滚动视图与内容一起向上滚动，并将当前文本字段向上推。

Answer 3

您应该首先尝试使用以下代码定位UITextField 实例。

extension UIView {

    func firstResponder() -> UIView? {
        if self.isFirstResponder() {
            return self
        }

        for subview in self.subviews {
            if subview.isFirstResponder() {
                return subview
            }
        }

        return nil
    }

}

在keyboardWillShow: 函数中决定当键盘出现时文本字段是否可见。

func keyboardWillShow(notification:NSNotification) {
    if keyboardIsPresent == false {
        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue(),
            let inputView = self.ContentView.firstResponder()
            where inputView.frame.maxY > self.ContentView.frame.size.height - keyboardSize.height {

            self.ContentView.frame.origin.y -= keyboardSize.height
            keyboardIsPresent = true

        }
    }
}

如果视图被移开，则仅在隐藏功能中将视图移回。