当键盘可见时如何使 UITextView 一直滚动到底部

Question

我有一个带有几页文本的可编辑 UITextView。当用户点击里面并调出键盘时，它会隐藏文本的底部，您无法滚动查看它。

是否有一些明显/简单/标准的方法来处理这个问题？我认为这是一个常见问题。我假设您必须在键盘启动时调整文本视图的大小，或者类似的东西？

另外，当他们点击页面下半部分的文本视图时，如何让它自动滚动，以便在键盘出现时他们点击的行是可见的？或者如果我在键盘出现时调整文本视图的大小，这是否会自动处理。

非常感谢大家

Answer 1

此处已对此进行了广泛讨论：How to make a UITextField move up when keyboard is present?

我个人过去曾使用过 Shiun 的解决方案，效果很好。

更新： 如果您不想使用该方法，一个稍微简单的方法是在键盘显示时调整文本字段的大小。最好按照我上面发布的链接上的说明进行操作，因为 KeyboardWillShow 通知将使您能够访问键盘高度。

首先设置UITextField的delegate = self.那么：

-(void)textFieldDidBeginEditing:(UITextField *)textField { // This is where the keyboard becomes visible
    textField.frame = CGRectMake(textField.frame.origin.x, textField.frame.origin.y, textField.frame.size.width, textField.frame.size.height-100);
}

-(void)textFieldDidEndEditing:(UITextField *)textField { // This is where the keyboard hides itself
    textField.frame = CGRectMake(textField.frame.origin.x, textField.frame.origin.y, textField.frame.size.width, textField.frame.size.height+100);
}

您可以根据您的方向等调整 100。如果您想添加一些动画，您可以这样做：

-(void)textFieldDidBeginEditing:(UITextField *)textField { // This is where the keyboard becomes visible
        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDelegate:self];
        [UIView setAnimationDuration:0.5];
        [UIView setAnimationBeginsFromCurrentState:YES];
        textField.frame = CGRectMake(textField.frame.origin.x, textField.frame.origin.y, textField.frame.size.width, textField.frame.size.height-100);
        [UIView commitAnimations];
    }

    -(void)textFieldDidEndEditing:(UITextField *)textField { // This is where the keyboard hides itself 
        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDelegate:self];
        [UIView setAnimationDuration:0.5];
        [UIView setAnimationBeginsFromCurrentState:YES];
        textField.frame = CGRectMake(textField.frame.origin.x, textField.frame.origin.y, textField.frame.size.width, textField.frame.size.height+100);
        [UIView commitAnimations];
    }

Answer 2

当编辑开始时，这会很好地将您的 UITextView 滚动到键盘顶部。如果您的 UITextView 具有动态高度（键入时自动增长/自动调整大小），这也将起作用。在 iOS 7 中测试。

调用您的键盘观察者方法并将 UITextView 委托设置为当前类：

- (void)viewDidLoad
{
    ...
    [self observeKeyboard];
    textView.delegate = (id)self;
}

为 UIKeyboardDidShowNotification 和 UIKeyboardWillShowNotification 添加键盘观察器：

- (void)observeKeyboard
{
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidShow:) name:UIKeyboardDidShowNotification object:nil];
}

获取键盘大小：

- (void)keyboardWillShow:(NSNotification *)notification
{
    CGSize keyboardSize = [[[notification userInfo] objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
    _keyboardHeight = keyboardSize.height;
} 

- (void)keyboardDidShow:(NSNotification *)notification
{
    CGSize keyboardSize = [[[notification userInfo] objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
    _keyboardHeight = keyboardSize.height;
}

当 UITextView 开始编辑或值改变时调用scrollKeyboardToTextView:

- (void)textViewDidBeginEditing:(UITextView *)textView
{
    [self scrollKeyboardToTextView:textView];
}

- (void)textViewDidChange:(UITextView *)textView
{
    [self scrollKeyboardToTextView:textView];
}

将带有动画的 UITextView 滚动到键盘顶部：

- (void)scrollKeyboardToTextView:(UITextView *)textView
{
    UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, _keyboardHeight, 0.0);
    self.scrollView.contentInset = contentInsets;
    self.scrollView.scrollIndicatorInsets = contentInsets;

    CGRect aRect = self.view.frame;
    aRect.size.height -= _keyboardHeight;
    CGPoint origin = textView.frame.origin;
    origin.y -= self.scrollView.contentOffset.y;
    origin.y += textView.frame.size.height;

    CGPoint scrollPoint = CGPointMake(0.0, textView.frame.origin.y + textView.frame.size.height - (aRect.size.height));
    [self.scrollView setContentOffset:scrollPoint animated:YES];
}