我正在使用一个UITextView可以通过点击“更多”按钮进行扩展的工具。问题如下：
在iOS6上我用这个，
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 上返回的值与在 iOS6 上contentSize.height返回的值不同（远小于）。为什么是这样？如何解决？
内容大小属性不再像在 iOS 6 上那样工作。使用其他人建议的 sizeToFit 可能会或可能不会工作，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;
}
}
尝试以下链接中的答案，layoutIfNeeded应该在之前调用contentSize。
iOS7 UITextView contentsize.height 替代
答案：
在 iOS7 中，UITextView用于NSLayoutManager布局文本：
// 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修复contentSize：
textView.layoutManager.allowsNonContiguousLayout = NO;
这个链接似乎有答案。
使用前必须sizeToFit先使用contentSize。
Try with following code, Its will be work in both iOS6 and 7, please try it.
CGSize myTextViewSize = [self.myTextView sizeThatFits:CGSizeMake(self.myTextView.frame.size.width, FLT_MAX)];
self.myTextView.height = myTextViewSize.height;
NSLog(@"%f", self.myTextView.height);