使用属性文本在UITextView中重绘NSTextAttachments [英] Redrawing NSTextAttachments in an UITextView with attributed text

问题描述

我有一个覆盖的NSTextAttachment子类
attachmentBoundsForTextContainer：proposedLineFragment：glyphPosition：characterIndex：
imageForBounds：textContainer：characterIndex ：。

I have a NSTextAttachment subclass with overridden
attachmentBoundsForTextContainer:proposedLineFragment:glyphPosition:characterIndex:
imageForBounds:textContainer:characterIndex:.

我需要在某些时候重新绘制附件。在UITextView上调用 setNeedsDisplay 不起作用。

I need to redraw the attachment(s) at some point. Calling setNeedsDisplay on the UITextView doesn't work.

任何想法？我想避免重新创建附件和/或属性字符串。

Any ideas? I'd like to avoid recreating attachments and/or the attributed string.

推荐答案

你会想要使用 textView.layoutManager 的方法。

• invalidateDisplayCharacterRange：
  
  
  
  • imageForBounds：textContainer：characterIndex：将再次被调用。
  
  
  • attachmentBoundsForTextContainer：[...]索引：将不再再次调用。
  
  
  • 如果图片已使用另一个相同尺寸更改，那就太好了。
  
  
  • invalidateDisplayCharacterRange:
    • imageForBounds:textContainer:characterIndex: will be called again.
    • attachmentBoundsForTextContainer:[...]Index: will not be called again.
    • Good if the image has been changed with another one of the same size.
    
    
    • imageForBounds：textContainer：characterIndex ：将再次被调用。
    
    
    • attachmentBoundsForTextContainer：[...] index：将再次被调用。
    
    
    • 如果图像已被另一个不同 strong> size。
    
    
    • imageForBounds:textContainer:characterIndex: will be called again.
    • attachmentBoundsForTextContainer:[...]Index: will be called again.
    • Good if the image has been changed with another one of a different size.

    如果您只想更新单个附件，可能会发现我写的这个帮助方法很有用：

    If you just want to update a single attachment, you may find this helper method I wrote helpful:

    - (NSRange)rangeOfAttachment:(NSTextAttachment *)attachment {
        __block NSRange ret;
        [self.textStorage enumerateAttribute:NSAttachmentAttributeName
                                     inRange:NSMakeRange(0, self.textStorage.length)
                                     options:0
                                  usingBlock:^(id value, NSRange range, BOOL *stop) {
                                      if (attachment == value) {
                                          ret = range;
                                          *stop = YES;
                                      }
                                  }];
        return ret;
    }
    

    您可以传递结果 NSRange 到这些无效方法中的任何一个的第一个参数。对于第二种方法的 actualCharacterRange：参数，我一直在传递 NULL 而没有任何问题。

    You can pass the resulting NSRange of this method to the first argument of either of those invalidate methods. For the actualCharacterRange: argument of the second method, I've been passing in NULL without any problems.

    这篇关于使用属性文本在UITextView中重绘NSTextAttachments的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！