UITextView 末尾的省略号

Question

如果我有多行不可滚动的 UITextView，其文本长度超过了可见区域的容纳范围，那么文本就会像这样被截断：

Congress shall make no law respecting 
an establishment of religion, or 

如何让文本在文本截断位置处显示省略号，像这样

Congress shall make no law respecting
an establishment of religion, or … 

其他控件（如标签和按钮）也具有此功能。

Answer 1

为什么不使用 UILabel 将 numberOfLines 设置为适当的值并免费获得该功能？

Answer 2

UITextView 设计为当字符串大于视图可以显示的内容时滚动。确保您已在代码或 xib 中正确设置锚定和自动调整大小属性。

这是 博客文章。

@interface NSString (TruncateToWidth)
- (NSString*)stringByTruncatingToWidth:(CGFloat)width withFont:(UIFont *)font;
@end

---

#import "NSString+TruncateToWidth.h"

#define ellipsis @"…"

@implementation NSString (TruncateToWidth)

- (NSString*)stringByTruncatingToWidth:(CGFloat)width withFont:(UIFont *)font
{
  // Create copy that will be the returned result
  NSMutableString *truncatedString = [[self mutableCopy] autorelease];
  // Make sure string is longer than requested width
  if ([self sizeWithFont:font].width > width)
  {
    // Accommodate for ellipsis we'll tack on the end
    width -= [ellipsis sizeWithFont:font].width;
    // Get range for last character in string
    NSRange range = {truncatedString.length - 1, 1};

    // Loop, deleting characters until string fits within width
    while ([truncatedString sizeWithFont:font].width > width) 
    {
      // Delete character at end
      [truncatedString deleteCharactersInRange:range];
      // Move back another character
      range.location--;
    }

    // Append ellipsis
    [truncatedString replaceCharactersInRange:range withString:ellipsis];
  }

  return truncatedString;
}

@end

Answer 3

有人刚刚向我展示，在 iOS 7 及更高版本上使用 UITextView 做到这一点实际上非常容易：

UITextView *textView = [UITextView new];
textView.textContainer.lineBreakMode = NSLineBreakByTruncatingTail;