功能自动进行字符转换

Question

我有这段代码：

- (void)parser:(NSXMLParser *)parser foundCDATA:(NSData *)CDATABlock
{
    NSString *someString = [[NSString alloc] initWithData:CDATABlock encoding:NSUTF8StringEncoding];


   someString = [ someString stringByReplacingOccurrencesOfString:@"%" withString: @"&"  ];
   someString = [ someString stringByReplacingOccurrencesOfString:@"|" withString: @"|"  ];
   someString = [ someString stringByReplacingOccurrencesOfString:@" " withString: @" "  ];
   someString = [ someString stringByReplacingOccurrencesOfString:@"–" withString:@"-"];
   someString = [ someString stringByReplacingOccurrencesOfString:@"—" withString:@"——"];
   someString = [ someString stringByReplacingOccurrencesOfString:@"‘" withString:@"'"  ];
   someString = [ someString stringByReplacingOccurrencesOfString:@"’" withString:@"'"  ];
   someString = [ someString stringByReplacingOccurrencesOfString:@"‚" withString:@","  ];
   someString = [ someString stringByReplacingOccurrencesOfString:@"“" withString:@"\""  ];
   someString = [ someString stringByReplacingOccurrencesOfString:@"”" withString:@"\""  ];
   someString = [ someString stringByReplacingOccurrencesOfString:@"…" withString:@"..."];
   someString = [ someString stringByReplacingOccurrencesOfString:@"&#38;" withString:@"<"];
   someString = [ someString stringByReplacingOccurrencesOfString:@"&#39;" withString:@">"];
   someString = [ someString stringByReplacingOccurrencesOfString:@"&#8364;" withString:@"€"];
   someString = [ someString stringByReplacingOccurrencesOfString:@"&#8594;" withString:@"→"];

   if(nil != self.currentItemValue){
      [self.currentItemValue appendString:someString];
   }
}

是否有自动执行此字符转换的功能？

Answer 1

哇，这很糟糕，而且效率低下。至少，请切换到使用NSMutableString并进行内联替换。

在任何情况下，您都可以一次完成此操作，但您必须自己编写代码。您可以使用NSScanner或类似-rangeOfString:options:range:的方法来查找每个连续的实体，然后自己找出它的替代品。如果您在NSMutableString上运行，则可以用替换实体替换实体并继续搜索（在修改您的位置后（在NSScanner的情况下）或适当范围以考虑实体与实体之间的长度差异替代人物）。

Answer 2

不是像那样硬编码替换，而是有更好的方法。

这些实体的格式为：&# +十进制数+ ;。十进制数位是该字符的unicode代码点的基本10版本。因此，您可以搜索此格式的子字符串，提取数字，并将其直接转换为字符。

这是一种方法，使用RegexKitLite查找字符串：

NSString * source = @"& ' |   – — ‘ ’ ‚ “ ” … € →";

NSString * regex = @"&#(\\d+);";
NSArray * matches = [source arrayOfCaptureComponentsMatchedByRegex:regex];

NSMutableString * decodedSource = [source mutableCopy];
for (NSArray * match in matches) {
    NSString * fullMatch = [match objectAtIndex:0];
    NSString * decimalCode = [match objectAtIndex:1];

    unichar character = (unichar)[decimalCode intValue];
    NSString * replacement = [NSString stringWithFormat:@"%C", character];

    [decodedSource replaceOccurrencesOfString:fullMatch withString:replacement options:NSLiteralSearch range:NSMakeRange(0, [decodedSource length])];
}

NSLog(@"decoded: %@", decodedSource);
[decodedSource release];

在我的机器上，这会记录：

decoded: & ' |   – — ‘ ’ ‚ “ ” … € →

这不是最有效的方法（最糟糕的情况是O(nm)算法），但它是一个开始。 ：）