Question

我正在使用UITextView，可以通过点击“更多”按钮进行扩展。问题如下：

在iOS6上我使用它，

self.DescriptionTextView.text =  @"loong string";

if(self.DescriptionTextView.contentSize.height>self.DescriptionTextView.frame.size.height) { 
    //set up the more button
}

问题是在iOS7上contentSize.height返回的值（远小于）在iOS6上返回的值。为什么是这样？如何解决？

Answer 1

内容大小属性不再像在iOS 6上那样工作。使用sizeToFit可能会或可能不会使用sizeToFit，具体取决于许多因素。

它对我不起作用，所以我改用它：

- (CGFloat)measureHeightOfUITextView:(UITextView *)textView
{
    if (floor(NSFoundationVersionNumber) > NSFoundationVersionNumber_iOS_6_1)
    {
        // This is the code for iOS 7. contentSize no longer returns the correct value, so
        // we have to calculate it.
        //
        // This is partly borrowed from HPGrowingTextView, but I've replaced the
        // magic fudge factors with the calculated values (having worked out where
        // they came from)

        CGRect frame = textView.bounds;

        // Take account of the padding added around the text.

        UIEdgeInsets textContainerInsets = textView.textContainerInset;
        UIEdgeInsets contentInsets = textView.contentInset;

        CGFloat leftRightPadding = textContainerInsets.left + textContainerInsets.right + textView.textContainer.lineFragmentPadding * 2 + contentInsets.left + contentInsets.right;
        CGFloat topBottomPadding = textContainerInsets.top + textContainerInsets.bottom + contentInsets.top + contentInsets.bottom;

        frame.size.width -= leftRightPadding;
        frame.size.height -= topBottomPadding;

        NSString *textToMeasure = textView.text;
        if ([textToMeasure hasSuffix:@"\n"])
        {
            textToMeasure = [NSString stringWithFormat:@"%@-", textView.text];
        }

        // NSString class method: boundingRectWithSize:options:attributes:context is
        // available only on ios7.0 sdk.

        NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
        [paragraphStyle setLineBreakMode:NSLineBreakByWordWrapping];

        NSDictionary *attributes = @{ NSFontAttributeName: textView.font, NSParagraphStyleAttributeName : paragraphStyle };

        CGRect size = [textToMeasure boundingRectWithSize:CGSizeMake(CGRectGetWidth(frame), MAXFLOAT)
                                                  options:NSStringDrawingUsesLineFragmentOrigin
                                               attributes:attributes
                                                  context:nil];

        CGFloat measuredHeight = ceilf(CGRectGetHeight(size) + topBottomPadding);
        return measuredHeight;
    }
    else
    {
        return textView.contentSize.height;
    }
}

Answer 2

请尝试以下链接中的答案，layoutIfNeeded之前应调用contentSize。

iOS7 UITextView contentsize.height alternative

答案：

在iOS7中，UITextView使用NSLayoutManager来布局文字：

// If YES, then the layout manager may perform glyph generation and layout for a given portion of the text, without having glyphs or layout for preceding portions.  The default is NO.  Turning this setting on will significantly alter which portions of the text will have glyph generation or layout performed when a given generation-causing method is invoked.  It also gives significant performance benefits, especially for large documents.
@property(NS_NONATOMIC_IOSONLY) BOOL allowsNonContiguousLayout;

禁用allowsNonContiguousLayout来修复contentSize：

textView.layoutManager.allowsNonContiguousLayout = NO;

Answer 3

这link似乎有答案。

在使用sizeToFit之前，您必须先使用contentSize。

Answer 4

尝试使用以下代码，它将在iOS6和7中都有效，请尝试一下。

CGSize myTextViewSize = [self.myTextView sizeThatFits:CGSizeMake(self.myTextView.frame.size.width, FLT_MAX)];
self.myTextView.height = myTextViewSize.height;
NSLog(@"%f", self.myTextView.height);

iOS7中的UITextView内容大小不同

4 个答案: