Objective-C / Cocoa Touch中的HTML字符解码
首先，我发现这个： Objective C HTML escape / unescape ，但它不适用于我。
我的编码字符（来自RSS源，顺便说一句）看起来像这样： &
我搜索了整个网络，发现相关的讨论，但没有解决我的特定编码，我认为他们被称为十六进制字符。
这些被称为字符实体引用 。 当他们采取&#<number>;的形式&#<number>; 他们被称为数字实体引用 。 基本上，它是应该被替换的字节的字符串表示。 在& ，它代表ISO-8859-1字符编码方案中值为38的字符，即& 。
＆符号必须在RSS中编码的原因是它是一个保留的特殊字符。
你需要做的是解析字符串，并用一个匹配&#和;之间的值的字节替换实体; 。 我不知道有什么好的方法来做到这一点在客观的C，但这个堆栈溢出的问题可能会有所帮助。
编辑：自从两年前回答这个问题以后，有一些很好的解决方案。 请参阅下面的@Michael Waterfall的答案。
查看我的NSString类别的HTML 。 以下是可用的方法：
- (NSString *)stringByConvertingHTMLToPlainText; - (NSString *)stringByDecodingHTMLEntities; - (NSString *)stringByEncodingHTMLEntities; - (NSString *)stringWithNewLinesAsBRs; - (NSString *)stringByRemovingNewLinesAndWhitespace;
Daniel的那个基本上是非常好的，我在那里解决了一些问题：
-
删除了NSSCanner的跳过字符（否则两个连续实体之间的空格将被忽略
[扫描仪setCharactersToBeSkipped：无];
-
修复了当有孤立的'＆'符号解析（我不知道什么是“正确的”输出，我只是比较它与Firefox）：
例如
&#ABC DF & B' & C' Items (288)
这里是修改后的代码：
- (NSString *)stringByDecodingXMLEntities { NSUInteger myLength = [self length]; NSUInteger ampIndex = [self rangeOfString:@"&" options:NSLiteralSearch].location; // Short-circuit if there are no ampersands. if (ampIndex == NSNotFound) { return self; } // Make result string with some extra capacity. NSMutableString *result = [NSMutableString stringWithCapacity:(myLength * 1.25)]; // First iteration doesn't need to scan to & since we did that already, but for code simplicity's sake we'll do it again with the scanner. NSScanner *scanner = [NSScanner scannerWithString:self]; [scanner setCharactersToBeSkipped:nil]; NSCharacterSet *boundaryCharacterSet = [NSCharacterSet characterSetWithCharactersInString:@" \t\n\r;"]; do { // Scan up to the next entity or the end of the string. NSString *nonEntityString; if ([scanner scanUpToString:@"&" intoString:&nonEntityString]) { [result appendString:nonEntityString]; } if ([scanner isAtEnd]) { goto finish; } // Scan either a HTML or numeric character entity reference. if ([scanner scanString:@"&" intoString:NULL]) [result appendString:@"&"]; else if ([scanner scanString:@"'" intoString:NULL]) [result appendString:@"'"]; else if ([scanner scanString:@""" intoString:NULL]) [result appendString:@"\""]; else if ([scanner scanString:@"<" intoString:NULL]) [result appendString:@"<"]; else if ([scanner scanString:@">" intoString:NULL]) [result appendString:@">"]; else if ([scanner scanString:@"&#" intoString:NULL]) { BOOL gotNumber; unsigned charCode; NSString *xForHex = @""; // Is it hex or decimal? if ([scanner scanString:@"x" intoString:&xForHex]) { gotNumber = [scanner scanHexInt:&charCode]; } else { gotNumber = [scanner scanInt:(int*)&charCode]; } if (gotNumber) { [result appendFormat:@"%C", (unichar)charCode]; [scanner scanString:@";" intoString:NULL]; } else { NSString *unknownEntity = @""; [scanner scanUpToCharactersFromSet:boundaryCharacterSet intoString:&unknownEntity]; [result appendFormat:@"&#%@%@", xForHex, unknownEntity]; //[scanner scanUpToString:@";" intoString:&unknownEntity]; //[result appendFormat:@"&#%@%@;", xForHex, unknownEntity]; NSLog(@"Expected numeric character entity but got &#%@%@;", xForHex, unknownEntity); } } else { NSString *amp; [scanner scanString:@"&" intoString:&]; //an isolated & symbol [result appendString:amp]; /* NSString *unknownEntity = @""; [scanner scanUpToString:@";" intoString:&unknownEntity]; NSString *semicolon = @""; [scanner scanString:@";" intoString:&semicolon]; [result appendFormat:@"%@%@", unknownEntity, semicolon]; NSLog(@"Unsupported XML character entity %@%@", unknownEntity, semicolon); */ } } while (![scanner isAtEnd]); finish: return result; }
从iOS 7开始，可以使用带有NSHTMLTextDocumentType属性的NSAttributedString本地解码HTML字符：
NSString *htmlString = @" & & < > ™ © ♥ ♣ ♠ ♦"; NSData *stringData = [htmlString dataUsingEncoding:NSUTF8StringEncoding]; NSDictionary *options = @{NSDocumentTypeDocumentAttribute:NSHTMLTextDocumentType}; NSAttributedString *decodedString; decodedString = [[NSAttributedString alloc] initWithData:stringData options:options documentAttributes:NULL error:NULL];
解码的属性字符串现在将显示为：＆＆<>™©♥♣♠♦。
注意：这只有在主线程上调用才会起作用。
似乎没有人提到最简单的选择之一： Google Toolbox for Mac
（尽管名字，这也适用于iOS。）
https://github.com/google/google-toolbox-for-mac/blob/master/Foundation/GTMNSString%2BHTML.h
/// Get a string where internal characters that are escaped for HTML are unescaped // /// For example, '&' becomes '&' /// Handles   and 2 cases as well /// // Returns: // Autoreleased NSString // - (NSString *)gtm_stringByUnescapingFromHTML;
而且我只能在项目中包含三个文件：头文件，实现文件和GTMDefines.h 。
我应该在GitHub上发布这个东西。 这是一个NSString的类别，使用NSScanner来实现，并处理十六进制和十进制数字字符实体以及通常的符号。
此外，它处理格式错误的字符串（当你有一个无效的字符序列），相对优雅，这是我发布的应用程序 ，使用此代码是至关重要的。
- (NSString *)stringByDecodingXMLEntities { NSUInteger myLength = [self length]; NSUInteger ampIndex = [self rangeOfString:@"&" options:NSLiteralSearch].location; // Short-circuit if there are no ampersands. if (ampIndex == NSNotFound) { return self; } // Make result string with some extra capacity. NSMutableString *result = [NSMutableString stringWithCapacity:(myLength * 1.25)]; // First iteration doesn't need to scan to & since we did that already, but for code simplicity's sake we'll do it again with the scanner. NSScanner *scanner = [NSScanner scannerWithString:self]; do { // Scan up to the next entity or the end of the string. NSString *nonEntityString; if ([scanner scanUpToString:@"&" intoString:&nonEntityString]) { [result appendString:nonEntityString]; } if ([scanner isAtEnd]) { goto finish; } // Scan either a HTML or numeric character entity reference. if ([scanner scanString:@"&" intoString:NULL]) [result appendString:@"&"]; else if ([scanner scanString:@"'" intoString:NULL]) [result appendString:@"'"]; else if ([scanner scanString:@""" intoString:NULL]) [result appendString:@"\""]; else if ([scanner scanString:@"<" intoString:NULL]) [result appendString:@"<"]; else if ([scanner scanString:@">" intoString:NULL]) [result appendString:@">"]; else if ([scanner scanString:@"&#" intoString:NULL]) { BOOL gotNumber; unsigned charCode; NSString *xForHex = @""; // Is it hex or decimal? if ([scanner scanString:@"x" intoString:&xForHex]) { gotNumber = [scanner scanHexInt:&charCode]; } else { gotNumber = [scanner scanInt:(int*)&charCode]; } if (gotNumber) { [result appendFormat:@"%C", charCode]; } else { NSString *unknownEntity = @""; [scanner scanUpToString:@";" intoString:&unknownEntity]; [result appendFormat:@"&#%@%@;", xForHex, unknownEntity]; NSLog(@"Expected numeric character entity but got &#%@%@;", xForHex, unknownEntity); } [scanner scanString:@";" intoString:NULL]; } else { NSString *unknownEntity = @""; [scanner scanUpToString:@";" intoString:&unknownEntity]; NSString *semicolon = @""; [scanner scanString:@";" intoString:&semicolon]; [result appendFormat:@"%@%@", unknownEntity, semicolon]; NSLog(@"Unsupported XML character entity %@%@", unknownEntity, semicolon); } } while (![scanner isAtEnd]); finish: return result; }
这是我使用RegexKitLite框架的方式：
-(NSString*) decodeHtmlUnicodeCharacters: (NSString*) html { NSString* result = [html copy]; NSArray* matches = [result arrayOfCaptureComponentsMatchedByRegex: @"\\&#([\\d]+);"]; if (![matches count]) return result; for (int i=0; i<[matches count]; i++) { NSArray* array = [matches objectAtIndex: i]; NSString* charCode = [array objectAtIndex: 1]; int code = [charCode intValue]; NSString* character = [NSString stringWithFormat:@"%C", code]; result = [result stringByReplacingOccurrencesOfString: [array objectAtIndex: 0] withString: character]; } return result;
}
希望这会帮助别人。
你可以使用这个函数来解决这个问题。
+ (NSString*) decodeHtmlUnicodeCharactersToString:(NSString*)str { NSMutableString* string = [[NSMutableString alloc] initWithString:str]; // #&39; replace with ' NSString* unicodeStr = nil; NSString* replaceStr = nil; int counter = -1; for(int i = 0; i < [string length]; ++i) { unichar char1 = [string characterAtIndex:i]; for (int k = i + 1; k < [string length] - 1; ++k) { unichar char2 = [string characterAtIndex:k]; if (char1 == '&' && char2 == '#' ) { ++counter; unicodeStr = [string substringWithRange:NSMakeRange(i + 2 , 2)]; // read integer value ie, 39 replaceStr = [string substringWithRange:NSMakeRange (i, 5)]; // #&39; [string replaceCharactersInRange: [string rangeOfString:replaceStr] withString:[NSString stringWithFormat:@"%c",[unicodeStr intValue]]]; break; } } } [string autorelease]; if (counter > 1) return [self decodeHtmlUnicodeCharactersToString:string]; else return string; }
其实，Michael Waterfall的MWFeedParser框架（参考他的回答）已经被rmchaara分享了，他已经用ARC支持更新了它。
你可以在这里找到Github
它真的很好，我用stringByDecodingHTMLEntities方法，并完美地工作。
这是一个Swiet版本的Walty Yeung的回答 ：
extension String { static private let mappings = [""" : "\"","&" : "&", "<" : "<", ">" : ">"," " : " ","¡" : "¡","¢" : "¢","£" : " £","¤" : "¤","¥" : "¥","¦" : "¦","§" : "§","¨" : "¨","©" : "©","ª" : " ª","«" : "«","¬" : "¬","®" : "®","¯" : "¯","°" : "°","±" : "±","² " : "²","³" : "³","´" : "´","µ" : "µ","¶" : "¶","·" : "·","¸" : "¸","¹" : "¹","º" : "º","»" : "»&","frac14" : "¼","½" : "½","¾" : "¾","¿" : "¿","×" : "×","÷" : "÷","Ð" : "Ð","ð" : "ð","Þ" : "Þ","þ" : "þ","Æ" : "Æ","æ" : "æ","&OElig" : "Œ","&oelig" : "œ","Å" : "Å","Ø" : "Ø","Ç" : "Ç","ç" : "ç","ß" : "ß","Ñ" : "Ñ","ñ":"ñ",] func stringByDecodingXMLEntities() -> String { guard let _ = self.rangeOfString("&", options: [.LiteralSearch]) else { return self } var result = "" let scanner = NSScanner(string: self) scanner.charactersToBeSkipped = nil let boundaryCharacterSet = NSCharacterSet(charactersInString: " \t\n\r;") repeat { var nonEntityString: NSString? = nil if scanner.scanUpToString("&", intoString: &nonEntityString) { if let s = nonEntityString as? String { result.appendContentsOf(s) } } if scanner.atEnd { break } var didBreak = false for (k,v) in String.mappings { if scanner.scanString(k, intoString: nil) { result.appendContentsOf(v) didBreak = true break } } if !didBreak { if scanner.scanString("&#", intoString: nil) { var gotNumber = false var charCodeUInt: UInt32 = 0 var charCodeInt: Int32 = -1 var xForHex: NSString? = nil if scanner.scanString("x", intoString: &xForHex) { gotNumber = scanner.scanHexInt(&charCodeUInt) } else { gotNumber = scanner.scanInt(&charCodeInt) } if gotNumber { let newChar = String(format: "%C", (charCodeInt > -1) ? charCodeInt : charCodeUInt) result.appendContentsOf(newChar) scanner.scanString(";", intoString: nil) } else { var unknownEntity: NSString? = nil scanner.scanUpToCharactersFromSet(boundaryCharacterSet, intoString: &unknownEntity) let h = xForHex ?? "" let u = unknownEntity ?? "" result.appendContentsOf("&#\(h)\(u)") } } else { scanner.scanString("&", intoString: nil) result.appendContentsOf("&") } } } while (!scanner.atEnd) return result } }
就好像你需要另一个解决方案！ 这个很简单，很有效：
@interface NSString (NSStringCategory) - (NSString *) stringByReplacingISO8859Codes; @end @implementation NSString (NSStringCategory) - (NSString *) stringByReplacingISO8859Codes { NSString *dataString = self; do { //*** See if string contains &# prefix NSRange range = [dataString rangeOfString: @"&#" options: NSRegularExpressionSearch]; if (range.location == NSNotFound) { break; } //*** Get the next three charaters after the prefix NSString *isoHex = [dataString substringWithRange: NSMakeRange(range.location + 2, 3)]; //*** Create the full code for replacement NSString *isoString = [NSString stringWithFormat: @"&#%@;", isoHex]; //*** Convert to decimal integer unsigned decimal = 0; NSScanner *scanner = [NSScanner scannerWithString: [NSString stringWithFormat: @"0%@", isoHex]]; [scanner scanHexInt: &decimal]; //*** Use decimal code to get unicode character NSString *unicode = [NSString stringWithFormat:@"%C", decimal]; //*** Replace all occurences of this code in the string dataString = [dataString stringByReplacingOccurrencesOfString: isoString withString: unicode]; } while (TRUE); //*** Loop until we hit the NSNotFound return dataString; } @end
如果字符实体引用是字符串，例如@"2318" ，则可以使用strtoul提取带有正确unicode字符的重新编码的NSString;
NSString *unicodePoint = @"2318" unichar iconChar = (unichar) strtoul(unicodePoint.UTF8String, NULL, 16); NSString *recoded = [NSString stringWithFormat:@"%C", iconChar]; NSLog(@"recoded: %@", recoded"); // prints out "recoded: ⌘"
Jugale答案的Swift 3版本
extension String { static private let mappings = [""" : "\"","&" : "&", "<" : "<", ">" : ">"," " : " ","¡" : "¡","¢" : "¢","£" : " £","¤" : "¤","¥" : "¥","¦" : "¦","§" : "§","¨" : "¨","©" : "©","ª" : " ª","«" : "«","¬" : "¬","®" : "®","¯" : "¯","°" : "°","±" : "±","² " : "²","³" : "³","´" : "´","µ" : "µ","¶" : "¶","·" : "·","¸" : "¸","¹" : "¹","º" : "º","»" : "»&","frac14" : "¼","½" : "½","¾" : "¾","¿" : "¿","×" : "×","÷" : "÷","Ð" : "Ð","ð" : "ð","Þ" : "Þ","þ" : "þ","Æ" : "Æ","æ" : "æ","&OElig" : "Œ","&oelig" : "œ","Å" : "Å","Ø" : "Ø","Ç" : "Ç","ç" : "ç","ß" : "ß","Ñ" : "Ñ","ñ":"ñ",] func stringByDecodingXMLEntities() -> String { guard let _ = self.range(of: "&", options: [.literal]) else { return self } var result = "" let scanner = Scanner(string: self) scanner.charactersToBeSkipped = nil let boundaryCharacterSet = CharacterSet(charactersIn: " \t\n\r;") repeat { var nonEntityString: NSString? = nil if scanner.scanUpTo("&", into: &nonEntityString) { if let s = nonEntityString as? String { result.append(s) } } if scanner.isAtEnd { break } var didBreak = false for (k,v) in String.mappings { if scanner.scanString(k, into: nil) { result.append(v) didBreak = true break } } if !didBreak { if scanner.scanString("&#", into: nil) { var gotNumber = false var charCodeUInt: UInt32 = 0 var charCodeInt: Int32 = -1 var xForHex: NSString? = nil if scanner.scanString("x", into: &xForHex) { gotNumber = scanner.scanHexInt32(&charCodeUInt) } else { gotNumber = scanner.scanInt32(&charCodeInt) } if gotNumber { let newChar = String(format: "%C", (charCodeInt > -1) ? charCodeInt : charCodeUInt) result.append(newChar) scanner.scanString(";", into: nil) } else { var unknownEntity: NSString? = nil scanner.scanUpToCharacters(from: boundaryCharacterSet, into: &unknownEntity) let h = xForHex ?? "" let u = unknownEntity ?? "" result.append("&#\(h)\(u)") } } else { scanner.scanString("&", into: nil) result.append("&") } } } while (!scanner.isAtEnd) return result } }
