我使用下面的代码来突出显示来自这个Github Sample的一行.由于每行都有两个换行符,我想在突出显示实际句子之后我还可以获得上一个和下一个换行符并突出显示它们.但结果并不像我想要的那样.

// 1. create some fonts
UIFontDescriptor* fontDescriptor = [UIFontDescriptor
                                    preferredFontDescriptorWithTextStyle:UIFontTextStyleBody];
UIFontDescriptor* boldFontDescriptor = [fontDescriptor
                                        fontDescriptorWithSymbolicTraits:UIFontDescriptorTraitBold];
UIFont* boldFont =  [UIFont fontWithDescriptor:boldFontDescriptor size: 0.0];
UIFont* normalFont =  [UIFont preferredFontForTextStyle:UIFontTextStyleBody];

if (!_highlightedWorld) {
    _highlightedWorld = @"";
}

// Search for the highlighted world by using regex and highlight
NSString* regexStr = _highlightedWorld;
NSRegularExpression* regex = [NSRegularExpression
                              regularExpressionWithPattern:regexStr
                              options:0
                              error:nil];

// Highlighted attributes (Cyan font color,Bold)
NSDictionary* boldAttributes = @{ NSFontAttributeName : boldFont,NSBackgroundColorAttributeName    :   [UIColor cyanColor]};
//Normal attributes
NSDictionary* normalAttributes = @{ NSFontAttributeName : normalFont,NSBackgroundColorAttributeName    :   [UIColor whiteColor] };

// If the textview has multiple matches,iterate over each match,and highlight each.
[regex enumerateMatchesInString:[_backingStore string]
                        options:0
                          range:searchRange
                     usingBlock:^(NSTextCheckingResult *match,NSMatchingFlags flags,BOOL *stop){

                         // Highlight the actual line
                         NSRange matchRange = [match rangeAtIndex:0];
                         [self addAttributes:boldAttributes range:matchRange];

                         // Get the newline after the highlighted sentence,and highlight it
                         // Check if we reached the end
                         if (matchRange.location+matchRange.length < [_backingStore string].length) {
                             [self addAttributes:boldAttributes range:NSMakeRange(matchRange.location+matchRange.length,1)];
                         }
                         // Get the newline before the highlighted sentence,and highlight it
                         // Check if we reached the beginning
                         if (matchRange.location != 0) {
                             [self addAttributes:boldAttributes range:NSMakeRange(matchRange.location-1,1)];
                         }

                         // 4. reset the style to the original
                         if (NSMaxRange(matchRange)+1 < self.length) {
                             [self addAttributes:normalAttributes
                                           range:NSMakeRange(NSMaxRange(matchRange)+1,1)];
                         }
                     }];