如何在NSString中捕獲多個特殊指示**字符**並在它們之間加粗？

Question

我遇到了一個問題，查找由一對**字符指示的多個子串，並將它們加粗。例如，在此的NSString：

The Fox has **ran** around the **corner** 

應改爲：狐狸已經跑圍繞角落

這裏是我的代碼：

NSString *questionString = queryString; 
NSMutableAttributedString *mutableAttributedString = [[NSMutableAttributedString alloc] initWithString:questionString]; 

NSRange range = [questionString rangeOfString:@"\\*{2}([^*]+)\\*{2}" options:NSRegularExpressionSearch]; 
if (range.location != NSNotFound) { 
    [mutableAttributedString setAttributes:@{NSFontAttributeName:[UIFont boldSystemFontOfSize:size]} range:range]; 
} 

[[mutableAttributedString mutableString] replaceOccurrencesOfString:@"**" withString:@"" options:NSCaseInsensitiveSearch range:NSMakeRange(0, queryString.length)]; 

return mutableAttributedString; 

這個代碼只捕獲1雙所以我回來的是：狐狸已經跑到了角落

有什麼想法？

Answer 1

你必須枚舉正則表達式的所有匹配。 這有點棘手，因爲當您刪除限制「**」對時，所有範圍都會移位。

這似乎做的工作：

NSString *questionString = @"The Fox has **ran** around the **corner**"; 
NSMutableAttributedString *mutableAttributedString = [[NSMutableAttributedString alloc] initWithString:questionString]; 

NSError *error = nil; 
NSString *pattern = @"(\\*{2})([^*]+)(\\*{2})"; 
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:pattern options:0 error:&error]; 

__block NSUInteger shift = 0; // number of characters removed so far 
[regex enumerateMatchesInString:questionString options:0 range:NSMakeRange(0, [questionString length]) 
    usingBlock:^(NSTextCheckingResult *result, NSMatchingFlags flags, BOOL *stop) { 
     NSRange r1 = [result rangeAtIndex:1]; // location of first ** 
     NSRange r2 = [result rangeAtIndex:2]; // location of word in between 
     NSRange r3 = [result rangeAtIndex:3]; // location of second ** 
     // Adjust locations according to the string modifications: 
     r1.location -= shift; 
     r2.location -= shift; 
     r3.location -= shift; 
     // Set attribute for the word: 
     [mutableAttributedString setAttributes:@{NSFontAttributeName:[UIFont boldSystemFontOfSize:12.0]} range:r2]; 
     // Remove the **'s: 
     [[mutableAttributedString mutableString] deleteCharactersInRange:r3]; 
     [[mutableAttributedString mutableString] deleteCharactersInRange:r1]; 
     // Update offset: 
     shift += r1.length + r3.length; 
    }]; 

結果（在調試器控制檯）：

The Fox has { 
}ran{ 
    NSFont = "<UICTFont: 0xc03efb0> font-family: \".HelveticaNeueInterface-MediumP4\"; font-weight: bold; font-style: normal; font-size: 12.00pt"; 
} around the { 
}corner{ 
    NSFont = "<UICTFont: 0xc03efb0> font-family: \".HelveticaNeueInterface-MediumP4\"; font-weight: bold; font-style: normal; font-size: 12.00pt"; 
}