更改框架时，UITextView 光标在框架下方答案

【问题标题】：UITextView cursor below frame when changing frame更改框架时，UITextView 光标在框架下方
【发布时间】：2013-08-28 04:59:56
【问题描述】：

我有一个UIViewCOntroller，其中包含一个UITextView。当键盘出现时，我会像这样调整它的大小：

#pragma mark - Responding to keyboard events

- (void)keyboardDidShow:(NSNotification *)notification
{
    NSDictionary* info = [notification userInfo];
    CGRect keyboardSize = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
    CGRect newTextViewFrame = self.textView.frame;
    newTextViewFrame.size.height -= keyboardSize.size.height + 70;
    self.textView.frame = newTextViewFrame;
    self.textView.backgroundColor = [UIColor yellowColor];
}

- (void)keyboardWillHide:(NSNotification *)notification
{
    NSDictionary* info = [notification userInfo];
    CGRect keyboardSize = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
    CGRect newTextViewFrame = self.textView.frame;
    newTextViewFrame.size.height += keyboardSize.size.height - 70;
    self.textView.frame = newTextViewFrame;
}

textView 似乎调整到正确的大小，但是当用户键入时，光标最终会出现在 textView 框架的“外部”。见下图：

黄色区域是UITextView框（不知道R键旁边的蓝线是什么）。我觉得这很有线。如果这有什么不同，我正在使用 iOS7。

有什么想法或提示吗？

更新

我有一个 UITextView 子类，它使用以下方法绘制水平线（如果有什么不同的话）：

- (void)drawRect:(CGRect)rect {

    //Get the current drawing context
    CGContextRef context = UIGraphicsGetCurrentContext();
    //Set the line color and width
    CGContextSetStrokeColorWithColor(context, [UIColor colorWithRed:229.0/255.0 green:244.0/255.0 blue:255.0/255.0 alpha:1].CGColor);
    CGContextSetLineWidth(context, 1.0f);
    //Start a new Path
    CGContextBeginPath(context);

    //Find the number of lines in our textView + add a bit more height to draw lines in the empty part of the view
    NSUInteger numberOfLines = (self.contentSize.height + rect.size.height) / self.font.lineHeight;

    CGFloat baselineOffset = 6.0f;

    //iterate over numberOfLines and draw each line
    for (int x = 0; x < numberOfLines; x++) {
        //0.5f offset lines up line with pixel boundary
        CGContextMoveToPoint(context, rect.origin.x, self.font.lineHeight*x + 0.5f + baselineOffset);
        CGContextAddLineToPoint(context, rect.size.width, self.font.lineHeight*x + 0.5f + baselineOffset);
    }

    // Close our Path and Stroke (draw) it
    CGContextClosePath(context);
    CGContextStrokePath(context);
}

【问题讨论】：

我遇到了同样的问题。似乎textView.font.lineHeight 没有考虑调整contentOffset。更正偏移委托的 textViewDidChange: 不起作用，因为它的值会以某种方式恢复。
好的，你是怎么解决的？
这可能只是某个未发布的、NDA 的 SDK 的问题吗？它是否适用于其他 iOS 版本？
这只是一种预感，但您是否尝试过在您的 keyboardDidShow 和 keyboardWillHide 方法中调用 [self.textView setNeedsLayout];？
我的第二个想法是：如果您使用的是 AutoLayout，请尝试设置高度约束。将该约束作为 IBOutlet 连接到您的视图控制器。尝试更改自动布局约束，而不是更改框架。请让我知道这是否适合您。

标签： ios objective-c cocoa-touch uitextview uikeyboard

【解决方案1】：

为什么不给你的文本视图一个contentInset（和一个匹配的scrollIndicatorInsets）而不是调整框架的大小？请记住，文本视图实际上是滚动视图。这是处理键盘（或其他）干扰的正确方法。

有关contentInset 的更多信息，请参阅this 问题。

这似乎还不够。仍然使用插入，因为这样更正确（尤其是在 iOS7 上，键盘是透明的），但您还需要对插入符号进行额外处理：

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self.textView setDelegate:self];
    self.textView.keyboardDismissMode = UIScrollViewKeyboardDismissModeInteractive;

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_keyboardWillShowNotification:) name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_keyboardWillHideNotification:) name:UIKeyboardWillHideNotification object:nil];
}

- (void)_keyboardWillShowNotification:(NSNotification*)notification
{
    UIEdgeInsets insets = self.textView.contentInset;
    insets.bottom += [notification.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue].size.height;
    self.textView.contentInset = insets;

    insets = self.textView.scrollIndicatorInsets;
    insets.bottom += [notification.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue].size.height;
    self.textView.scrollIndicatorInsets = insets;
}

- (void)_keyboardWillHideNotification:(NSNotification*)notification
{
    UIEdgeInsets insets = self.textView.contentInset;
    insets.bottom -= [notification.userInfo[UIKeyboardFrameBeginUserInfoKey] CGRectValue].size.height;
    self.textView.contentInset = insets;

    insets = self.textView.scrollIndicatorInsets;
    insets.bottom -= [notification.userInfo[UIKeyboardFrameBeginUserInfoKey] CGRectValue].size.height;
    self.textView.scrollIndicatorInsets = insets;
}

- (void)textViewDidBeginEditing:(UITextView *)textView
{
    _oldRect = [self.textView caretRectForPosition:self.textView.selectedTextRange.end];

    _caretVisibilityTimer = [NSTimer scheduledTimerWithTimeInterval:0.3 target:self selector:@selector(_scrollCaretToVisible) userInfo:nil repeats:YES];
}

- (void)textViewDidEndEditing:(UITextView *)textView
{
    [_caretVisibilityTimer invalidate];
    _caretVisibilityTimer = nil;
}

- (void)_scrollCaretToVisible
{
    //This is where the cursor is at.
    CGRect caretRect = [self.textView caretRectForPosition:self.textView.selectedTextRange.end];

    if(CGRectEqualToRect(caretRect, _oldRect))
        return;

    _oldRect = caretRect;

    //This is the visible rect of the textview.
    CGRect visibleRect = self.textView.bounds;
    visibleRect.size.height -= (self.textView.contentInset.top + self.textView.contentInset.bottom);
    visibleRect.origin.y = self.textView.contentOffset.y;

    //We will scroll only if the caret falls outside of the visible rect.
    if(!CGRectContainsRect(visibleRect, caretRect))
    {
        CGPoint newOffset = self.textView.contentOffset;

        newOffset.y = MAX((caretRect.origin.y + caretRect.size.height) - visibleRect.size.height + 5, 0);

        [self.textView setContentOffset:newOffset animated:YES];
    }
}

-(void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

很多工作，Apple 应该提供更好的处理插入符号的方法，但这是可行的。

【讨论】：

已测试，但我得到了相同的结果。
我将创建一个文本项目并尝试重现您的问题并进行修复。
谢谢，那太好了！
谢谢！很快就会尝试。
这里只需要注意一件事。这是 iOS 7 和 iOS 8 的最佳方法。但您需要记住，每次键盘更改时都会调用 UIKeyboardWillShowNotification。这意味着如果您在 iOS 8 中折叠预测输入面板，这将更改键盘高度并触发具有不同高度的事件。用户还可以在不关闭键盘的情况下拆分键盘。因此，与其对底部插图做 +=，不如真正做一个 '='。这样你就可以省去一些麻烦。隐藏事件也是如此，不要 -= 插入，直接将其设置为 0。

【解决方案2】：

我尝试过的所有其他答案对我来说都有点奇怪。使用NSTimer 执行滚动也意味着用户无法向上滚动，因为插入符号最终会离开屏幕并立即再次向下滚动。最后我还是坚持原来的方法，在键盘通知事件上更改UITextView帧，然后添加了以下方法：

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {
    // Whenever the user enters text, see if we need to scroll to keep the caret on screen
    [self scrollCaretToVisible];
    return YES;
}

- (void)scrollCaretToVisible
{
    //This is where the cursor is at.
    CGRect caretRect = [self.textView caretRectForPosition:self.textView.selectedTextRange.end];

    // Convert into the correct coordinate system
    caretRect = [self.view convertRect:caretRect fromView:self.textView];

    if(CGRectEqualToRect(caretRect, _oldRect)) {
        // No change
        return;
    }

    _oldRect = caretRect;

    //This is the visible rect of the textview.
    CGRect visibleRect = self.textView.frame;

    //We will scroll only if the caret falls outside of the visible rect.
    if (!CGRectContainsRect(visibleRect, caretRect))
    {
        // Work out how much the scroll position would have to change by to make the cursor visible
        CGFloat diff = (caretRect.origin.y + caretRect.size.height) - (visibleRect.origin.y + visibleRect.size.height);

        // If diff < 0 then this isn't to do with the iOS7 bug, so ignore
        if (diff > 0) {
            // Scroll just enough to bring the cursor back into view
            CGPoint newOffset = self.textView.contentOffset;
            newOffset.y += diff;
            [self.textView setContentOffset:newOffset animated:YES];
        }
    }
}

对我来说就像一个魅力

【讨论】：

您定义“差异”的行是正确的。但是，我建议也将 _textView.font.lineHeight*2 添加到 diff 中，否则如果用户在 textView 底部输入一个空行，部分光标将最终离开屏幕。

【解决方案3】：

已经有很多答案了，我发现在我的情况下它实际上要简单得多。在 keyboardWillShow 上，我调整了文本视图的 contentInset 并保持框架全屏。虽然scrollRangeToVisible: 不像其他许多人那样对我有用，但滚动视图方法（从 UITextView 继承）工作得很好。这对我有用：

- (void)textViewDidChange:(UITextView *)textView
{
    CGRect caret = [_textView caretRectForPosition:_textView.selectedTextRange.end];
    [_textView scrollRectToVisible:caret animated:YES];
}

【讨论】：

这对我来说是一个很好的答案。我的 UITextView 在 UIScrollView 内，所以我不仅要获得插入符号的位置，还要在我的 UIScrollView 滚动到正确的 UITextView 光标位置之前附加 textView 的框架原点 y 位置。

【解决方案4】：

Anders 和 Leo Natan 有很好的解决方案。但是，我需要稍微修改他们的答案以使滚动与 contentInset 一起正常工作。我面临的问题是 textViewDidBeginEditing: 在 keyboardWasShown: 之前被调用，因此 contentInset 更改不会在第一次通过时得到反映。这是我所做的：

在.h中

@interface NoteDayViewController : UIViewController <UITextViewDelegate>
{
    UIEdgeInsets noteTextViewInsets;
    UIEdgeInsets noteTextViewScrollIndicatorInsets;
    CGRect oldRect;
    NSTimer *caretVisibilityTimer;
    float noteViewBottomInset;
}
@property (weak, nonatomic) IBOutlet UITextView *noteTextView;

在.m中

- (void)registerForKeyboardNotifications
{
    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWasShown:)
                                             name:UIKeyboardDidShowNotification object:nil];

    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillBeHidden:)
                                             name:UIKeyboardWillHideNotification object:nil];
}

- (void)keyboardWasShown:(NSNotification*)aNotification
{
    CGFloat kbHeight = // get the keyboard height following your usual method

    UIEdgeInsets contentInsets = noteTextViewInsets;
    contentInsets.bottom = kbHeight;
    noteTextView.contentInset = contentInsets;

    UIEdgeInsets scrollInsets = noteTextViewScrollIndicatorInsets;
    scrollInsets.bottom = kbHeight;
    noteTextView.scrollIndicatorInsets = scrollInsets;

    [noteTextView setNeedsDisplay];
}

- (void)keyboardWillBeHidden:(NSNotification*)aNotification
{    
    noteTextView.contentInset = noteTextViewInsets;
    noteTextView.scrollIndicatorInsets = noteTextViewScrollIndicatorInsets;   
    [noteTextView setNeedsDisplay];
}

- (void)textViewDidBeginEditing:(UITextView *)textView
{
    oldRect = [noteTextView caretRectForPosition:noteTextView.selectedTextRange.end];
    noteViewBottomInset = noteTextView.contentInset.bottom;
    caretVisibilityTimer = [NSTimer scheduledTimerWithTimeInterval:0.3 target:self selector:@selector(scrollCaretToVisible) userInfo:nil repeats:YES];
}

- (void)textViewDidEndEditing:(UITextView *)textView
{
    [caretVisibilityTimer invalidate];
    caretVisibilityTimer = nil;
}

- (void)scrollCaretToVisible
{
    // This is where the cursor is at.
    CGRect caretRect = [noteTextView caretRectForPosition:noteTextView.selectedTextRange.end];

    // test if the caret has moved OR the bottom inset has changed
    if(CGRectEqualToRect(caretRect, oldRect) && noteViewBottomInset == noteTextView.contentInset.bottom)
    return;

    // reset these for next time this method is called
    oldRect = caretRect;
    noteViewBottomInset = noteTextView.contentInset.bottom;

    // this is the visible rect of the textview.
    CGRect visibleRect = noteTextView.bounds;
    visibleRect.size.height -= (noteTextView.contentInset.top + noteTextView.contentInset.bottom);
    visibleRect.origin.y = noteTextView.contentOffset.y;

    // We will scroll only if the caret falls outside of the visible rect.
    if (!CGRectContainsRect(visibleRect, caretRect))
    {
        CGPoint newOffset = noteTextView.contentOffset;
        newOffset.y = MAX((caretRect.origin.y + caretRect.size.height) - visibleRect.size.height, 0);
        [noteTextView setContentOffset:newOffset animated:NO]; // must be non-animated to work, not sure why
    }
}

【讨论】：

【解决方案5】：

这就是我最终做的事情，而且似乎可行：

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

    NSDictionary* info = [notification userInfo];
    CGSize kbSize = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;

     // self.textViewBottomSpace.constant = NSLayoutConstraint in IB (bottom position)
    self.textViewBottomSpace.constant = kbSize.height + 70;
    [self.textView setNeedsDisplay];
}


- (void)textViewKeyboardWillHide:(NSNotification *)notification
{
    self.textViewBottomSpace.constant = 0;
    [self.textView setNeedsDisplay];
}

- (void)scrollCaretToVisible
{
    //This is where the cursor is at.
    CGRect caretRect = [self.textView caretRectForPosition:self.textView.selectedTextRange.end];

    if(CGRectEqualToRect(caretRect, _oldRect))
        return;

    _oldRect = caretRect;

    //This is the visible rect of the textview.
    CGRect visibleRect = self.textView.bounds;
    visibleRect.size.height -= (self.textView.contentInset.top + self.textView.contentInset.bottom);
    visibleRect.origin.y = self.textView.contentOffset.y;

    //We will scroll only if the caret falls outside of the visible rect.
    if(!CGRectContainsRect(visibleRect, caretRect)) {
        CGPoint newOffset = self.textView.contentOffset;

        newOffset.y = MAX((caretRect.origin.y + caretRect.size.height) - visibleRect.size.height + 10, 0);

        [self.textView setContentOffset:newOffset animated:YES];
    }
}

- (void)textViewDidEndEditing:(UITextView *)textView
{    
    [_caretVisibilityTimer invalidate];
    _caretVisibilityTimer = nil;
}

- (void)textViewDidBeginEditing:(UITextView *)textView
{ 
    self.oldRect = [self.textView caretRectForPosition:self.textView.selectedTextRange.end];
    self.caretVisibilityTimer = [NSTimer scheduledTimerWithTimeInterval:0.3 target:self selector:@selector(scrollCaretToVisible) userInfo:nil repeats:YES];
}

【讨论】：

嗨安德斯，你能解释一下这一行 self.textviewBottomSpace.constant 我似乎无法在你的代码 sn-p 中找到它的声明。谢谢！
好吧，酷！用老式的方式改变框架应该有同样的效果。
我可以确认此解决方案适用于调整帧大小的方法。

【解决方案6】：

此问题的更简单解决方案是更新文本视图框架以响应 textViewDidBegingEditing 委托方法。有关详细信息，请参阅以下内容：

How to re-size UITextView when keyboard shown with iOS 7

【讨论】：

经过测试，但由于某种原因得到了与我原来的问题相同的结果。
@Anders 这真的很奇怪。这是一个非常令人沮丧的错误！我在这个上浪费了几个小时。

【解决方案7】：

对于那些在 UIScrollView 内有 UITextView 的用户，iOS

// This is the scroll view reference
@property (weak, nonatomic) IBOutlet UIScrollView *scrollView;

// Track the current UITextView
@property (weak, nonatomic) UITextView *activeField;

- (void)textViewDidBeginEditing:(UITextView *)textView
{
    self.activeField = textView;
}

- (void)textViewdDidEndEditing:(UITextView *)textView
{
    self.activeField = nil;
}

// Setup the keyboard observers that take care of the insets & initial scrolling
[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWasShown:)
                                             name:UIKeyboardDidShowNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillBeHidden:)
                                             name:UIKeyboardWillHideNotification object:nil];

- (void)keyboardWasShown:(NSNotification*)aNotification
{
    // Set the insets above the keyboard
    NSDictionary* info = [aNotification userInfo];
    CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;

    UIEdgeInsets insets = self.vForm.contentInset;
    insets.bottom += kbSize.height;
    self.vForm.contentInset = insets;

    insets = self.vForm.scrollIndicatorInsets;
    insets.bottom += kbSize.height;
    self.vForm.scrollIndicatorInsets = insets;

    // Scroll the active text field into view
    CGRect aRect = self.vForm.frame;
    aRect.size.height -= kbSize.height;
    CGPoint scrollPoint = CGPointMake(0.0, self.activeField.frame.origin.y);
    [self.scrollView setContentOffset:scrollPoint animated:YES];
}

- (void)keyboardWillBeHidden:(NSNotification*)aNotification
{
    UIEdgeInsets contentInsets = UIEdgeInsetsZero;
    self.vForm.contentInset = contentInsets;
    self.vForm.scrollIndicatorInsets = contentInsets;
}

// This is where the magic happens. Set the class with this method as the UITextView's delegate.
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {
    // Scroll the textview to the caret position
    [textView scrollRangeToVisible:textView.selectedRange];

    // Scroll the scrollview to the caret position within the textview
    CGRect targetRect = [textView caretRectForPosition:textView.selectedTextRange.end];
    targetRect.origin.y += self.activeField.frame.origin.y;
    [self.scrollView scrollRectToVisible:targetRect animated:YES];

    return YES;
}

我尝试包含大部分所需的胶水代码。唯一缺少的是设置 UITextView 的委托和关闭键盘。

花了 2 到 3 天的时间来弄清楚以前的工作。谢谢，苹果。

【讨论】：

【解决方案8】：

Angel Naydenov 上面的评论是对的，尤其是在从英文切换到日文键盘等显示提示的情况下。

切换键盘时，会调用UIKeyboardWillShowNotification，但不会调用UIKeyboardWillHideNotification。

所以你必须调整插图使用绝对值而不是使用+=。

不相关，[self.textView setContentOffset:newOffset animated:YES]; 在第二次显示键盘后实际上不会改变 iOS 7.1 中的图形，这可能是一个错误。我使用的解决方法是替换

[self.textView setContentOffset:newOffset animated:YES];

与

[UIView animateWithDuration:.25 animations:^{
        self.textView.contentOffset = newOffset;
 }];

【讨论】：

【解决方案9】：

Leo Natan，您的起步不错，但执行效率相对较低。这是一种使用更少代码的更好方法：

// Add Keyboard Notification Listeners in ViewDidLoad
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_keyboardWillShowNotification:) name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_keyboardWillHideNotification:) name:UIKeyboardWillHideNotification object:nil];


// And Add The Following Methods
- (void)_keyboardWillShowNotification:(NSNotification*)notification
{    
    CGRect textViewFrame = self.textView.frame;
    textViewFrame.size.height -= ([notification.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue].size.height + 4.0);
    self.textView.frame = textViewFrame;
}

- (void)_keyboardWillHideNotification:(NSNotification*)notification
{
    CGRect textViewFrame = self.textView.frame;
    textViewFrame.size.height += ([notification.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue].size.height + 4.0);
    self.textView.frame = textViewFrame;
}

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {

    NSRange typingRange = NSMakeRange(textView.text.length - 1, 1);
    [textView scrollRangeToVisible:typingRange];

    return YES;

}

- (void)dealloc {

    [[NSNotificationCenter defaultCenter] removeObserver:self];

}

【讨论】：

这不是 Leo Natan 解决方案的更有效实现，它是一种不同的解决方案，它没有解决 Leo 的 iOS 7 键盘透明度问题。正如 Leo 所说，使用 contentInset 和 scrollIndicatorInsets 是更“正确”的解决方案，而不是仅仅改变帧大小。