Objective-C 中的 NSString 标记化

Posted 2023-02-22

【中文标题】Objective-C 中的 NSString 标记化

【英文标题】：NSString tokenize in Objective-C

【发布时间】：2010-09-20 13:43:03

【问题描述】：

在 Objective-C 中标记/拆分 NSString 的最佳方法是什么？

【参考方案1】：

找到答案here：

NSString *string = @"oop:ack:bork:greeble:ponies";
NSArray *chunks = [string componentsSeparatedByString: @":"];

【讨论】：

作为对未来读者的参考，我想注意的是，相反的是[anArray componentsJoinedByString:@":"];。

谢谢，但是如何拆分由更多标记分隔的 NSString？ （如果你明白我的意思，我的英语不是很好）@Adam

@Adam，我想你想要的是componentsSeparatedByCharactersInSet。请参阅下面的答案。

【参考方案2】：

如果您只想拆分字符串，请使用-[NSString componentsSeparatedByString:]。如需更复杂的标记化，请使用 NSScanner 类。

【参考方案3】：

如果您的标记化需求更复杂，请查看我的开源 Cocoa 字符串标记/解析工具包：ParseKit：

http://parsekit.com

对于使用分隔符 char（如 ':'）的简单字符串拆分，ParseKit 肯定是矫枉过正。但同样，对于复杂的标记化需求，ParseKit 非常强大/灵活。

另见ParseKit Tokenization documentation。

【讨论】：

这还能用吗？我试过了，但遇到了一些错误，我不敢尝试修复自己。

嗯？活？ ParseKit 项目得到积极维护，是的。但是，这里的 cmets 不是提交项目错误的正确位置。如果您需要提交错误，它在 Google Code 和 Github 上。

听起来不错，但现在我无法删除我的反对票，除非您以某种方式编辑答案（网站规则）。也许您可以注意它的工作版本，或者它是否使用 ARC 等？或者你可以在某个地方添加一个空间，这取决于你:)

【参考方案4】：

每个人都提到过componentsSeparatedByString:，但你也可以使用CFStringTokenizer（请记住NSString 和CFString 是可以互换的），它也会标记自然语言（比如中文/日文不会在空格上分割单词)。

【讨论】：

而且，在 Mac OS X 10.6 及更高版本中，NSString 具有方法 enumerateLinesUsingBlock: 和 enumerateSubstringsInRange:options:usingBlock:，后者是 CFStringTokenizer 的基于块的版本。 developer.apple.com/mac/library/documentation/Cocoa/Reference/…:developer.apple.com/mac/library/documentation/Cocoa/Reference/…:

enumerate 方法在 ios 4 及更高版本中也可用。

【参考方案5】：

如果你想标记多个字符，你可以使用 NSString 的componentsSeparatedByCharactersInSet。 NSCharacterSet 有一些方便的预制集合，例如 whitespaceCharacterSet 和 illegalCharacterSet。它有 Unicode 范围的初始化器。

您还可以组合字符集并使用它们进行标记，如下所示：

// Tokenize sSourceEntityName on both whitespace and punctuation.
NSMutableCharacterSet *mcharsetWhitePunc = [[NSCharacterSet whitespaceAndNewlineCharacterSet] mutableCopy];
[mcharsetWhitePunc formUnionWithCharacterSet:[NSCharacterSet punctuationCharacterSet]];
NSArray *sarrTokenizedName = [self.sSourceEntityName componentsSeparatedByCharactersInSet:mcharsetWhitePunc];
[mcharsetWhitePunc release];

请注意，componentsSeparatedByCharactersInSet 如果连续遇到多个 charSet 成员，将生成空白字符串，因此您可能需要测试长度小于 1。

【讨论】：

不涉及空格根本不分隔所有逻辑标记的语言。糟糕的解决方案。

@uchuugaka 在这种情况下，您将使用不同的字符集或用于标记化的字符集。我只是用具体的例子来说明一个一般概念。

【参考方案6】：

我有一个案例，我必须在使用 ldapsearch 进行 LDAP 查询后拆分控制台输出。首先设置并执行 NSTask（我在这里找到了一个很好的代码示例：Execute a terminal command from a Cocoa app）。但后来我不得不拆分和解析输出，以便仅从 Ldap-query-output 中提取打印服务器名称。不幸的是，这是相当乏味的字符串操作，如果我们用简单的 C 数组操作来操作 C 字符串/数组，这根本就没有问题。所以这是我使用可可对象的代码。如果您有更好的建议，请告诉我。

//as the ldap query has to be done when the user selects one of our Active Directory Domains
//(an according comboBox should be populated with print-server names we discover from AD)
//my code is placed in the onSelectDomain event code

//the following variables are declared in the interface .h file as globals
@protected NSArray* aDomains;//domain combo list array
@protected NSMutableArray* aPrinters;//printer combo list array
@protected NSMutableArray* aPrintServers;//print server combo list array

@protected NSString* sLdapQueryCommand;//for LDAP Queries
@protected NSArray* aLdapQueryArgs;
@protected NSTask* tskLdapTask;
@protected NSPipe* pipeLdapTask;
@protected NSFileHandle* fhLdapTask;
@protected NSMutableData* mdLdapTask;

IBOutlet NSComboBox* comboDomain;
IBOutlet NSComboBox* comboPrinter;
IBOutlet NSComboBox* comboPrintServer;
//end of interface globals

//after collecting the print-server names they are displayed in an according drop-down comboBox
//as soon as the user selects one of the print-servers, we should start a new query to find all the
//print-queues on that server and display them in the comboPrinter drop-down list
//to find the shares/print queues of a windows print-server you need samba and the net -S command like this:
// net -S yourPrintServerName.yourBaseDomain.com -U yourLdapUser%yourLdapUserPassWord -W adm rpc share -l
//which dispalays a long list of the shares

- (IBAction)onSelectDomain:(id)sender

    static int indexOfLastItem = 0; //unfortunately we need to compare this because we are called also if the selection did not change!

    if ([comboDomain indexOfSelectedItem] != indexOfLastItem && ([comboDomain indexOfSelectedItem] != 0))
    

        indexOfLastItem = [comboDomain indexOfSelectedItem]; //retain this index for next call

    //the print-servers-list has to be loaded on a per univeristy or domain basis from a file dynamically or from AN LDAP-QUERY

    //initialize an LDAP-Query-Task or console-command like this one with console output
    /*

     ldapsearch -LLL -s sub -D "cn=yourLdapUser,ou=yourOuWithLdapUserAccount,dc=yourDomain,dc=com" -h "yourLdapServer.com" -p 3268 -w "yourLdapUserPassWord" -b "dc=yourBaseDomainToSearchIn,dc=com" "(&(objectcategory=computer)(cn=ps*))" "dn"

//our print-server names start with ps* and we want the dn as result, wich comes like this:

     dn: CN=PSyourPrintServerName,CN=Computers,DC=yourBaseDomainToSearchIn,DC=com

     */

    sLdapQueryCommand = [[NSString alloc] initWithString: @"/usr/bin/ldapsearch"];


    if ([[comboDomain stringValue] compare: @"firstDomain"] == NSOrderedSame) 

      aLdapQueryArgs = [NSArray arrayWithObjects: @"-LLL",@"-s", @"sub",@"-D", @"cn=yourLdapUser,ou=yourOuWithLdapUserAccount,dc=yourDomain,dc=com",@"-h", @"yourLdapServer.com",@"-p",@"3268",@"-w",@"yourLdapUserPassWord",@"-b",@"dc=yourFirstDomainToSearchIn,dc=com",@"(&(objectcategory=computer)(cn=ps*))",@"dn",nil];
    
    else 
      aLdapQueryArgs = [NSArray arrayWithObjects: @"-LLL",@"-s", @"sub",@"-D", @"cn=yourLdapUser,ou=yourOuWithLdapUserAccount,dc=yourDomain,dc=com",@"-h", @"yourLdapServer.com",@"-p",@"3268",@"-w",@"yourLdapUserPassWord",@"-b",@"dc=yourSecondDomainToSearchIn,dc=com",@"(&(objectcategory=computer)(cn=ps*))",@"dn",nil];

    


    //prepare and execute ldap-query task

    tskLdapTask = [[NSTask alloc] init];
    pipeLdapTask = [[NSPipe alloc] init];//instead of [NSPipe pipe]
    [tskLdapTask setStandardOutput: pipeLdapTask];//hope to get the tasks output in this file/pipe

    //The magic line that keeps your log where it belongs, has to do with NSLog (see https://***.com/questions/412562/execute-a-terminal-command-from-a-cocoa-app and here http://www.cocoadev.com/index.pl?NSTask )
    [tskLdapTask setStandardInput:[NSPipe pipe]];

    //fhLdapTask  = [[NSFileHandle alloc] init];//would be redundand here, next line seems to do the trick also
    fhLdapTask = [pipeLdapTask fileHandleForReading];
    mdLdapTask  = [NSMutableData dataWithCapacity:512];//prepare capturing the pipe buffer which is flushed on read and can overflow, start with 512 Bytes but it is mutable, so grows dynamically later
    [tskLdapTask setLaunchPath: sLdapQueryCommand];
    [tskLdapTask setArguments: aLdapQueryArgs];

#ifdef bDoDebug
    NSLog (@"sLdapQueryCommand: %@\n", sLdapQueryCommand);
    NSLog (@"aLdapQueryArgs: %@\n", aLdapQueryArgs );
    NSLog (@"tskLdapTask: %@\n", [tskLdapTask arguments]);
#endif

    [tskLdapTask launch];

    while ([tskLdapTask isRunning]) 
      [mdLdapTask appendData: [fhLdapTask readDataToEndOfFile]];
    
    [tskLdapTask waitUntilExit];//might be redundant here.

    [mdLdapTask appendData: [fhLdapTask readDataToEndOfFile]];//add another read for safety after process/command stops

    NSString* sLdapOutput = [[NSString alloc] initWithData: mdLdapTask encoding: NSUTF8StringEncoding];//convert output to something readable, as NSData and NSMutableData are mere byte buffers

#ifdef bDoDebug
    NSLog(@"LdapQueryOutput: %@\n", sLdapOutput);
#endif

    //Ok now we have the printservers from Active Directory, lets parse the output and show the list to the user in its combo box
    //output is formatted as this, one printserver per line
    //dn: CN=PSyourPrintServer,OU=Computers,DC=yourBaseDomainToSearchIn,DC=com

    //so we have to search for "dn: CN=" to retrieve each printserver's name
    //unfortunately splitting this up will give us a first line containing only "" empty string, which we can replace with the word "choose"
    //appearing as first entry in the comboBox

    aPrintServers = (NSMutableArray*)[sLdapOutput componentsSeparatedByString:@"dn: CN="];//split output into single lines and store it in the NSMutableArray aPrintServers

#ifdef bDoDebug
    NSLog(@"aPrintServers: %@\n", aPrintServers);
#endif

    if ([[aPrintServers objectAtIndex: 0 ] compare: @"" options: NSLiteralSearch] == NSOrderedSame)
      [aPrintServers replaceObjectAtIndex: 0 withObject: slChoose];//replace with localized string "choose"

#ifdef bDoDebug
      NSLog(@"aPrintServers: %@\n", aPrintServers);
#endif

    

//Now comes the tedious part to extract only the print-server-names from the single lines
    NSRange r;
    NSString* sTemp;

    for (int i = 1; i < [aPrintServers count]; i++) //skip first line with "choose". To get rid of the rest of the line, we must isolate/preserve the print server's name to the delimiting comma and remove all the remaining characters
      sTemp = [aPrintServers objectAtIndex: i];
      sTemp = [sTemp stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewlineCharacterSet]];//remove newlines and line feeds

#ifdef bDoDebug
      NSLog(@"sTemp: %@\n", sTemp);
#endif
      r = [sTemp rangeOfString: @","];//now find first comma to remove the whole rest of the line
      //r.length = [sTemp lengthOfBytesUsingEncoding:NSUTF8StringEncoding];
      r.length = [sTemp length] - r.location;//calculate number of chars between first comma found and lenght of string
#ifdef bDoDebug
      NSLog(@"range: %i, %i\n", r.location, r.length);
#endif

      sTemp = [sTemp stringByReplacingCharactersInRange:r withString: @"" ];//remove rest of line
#ifdef bDoDebug
      NSLog(@"sTemp after replace: %@\n", sTemp);
#endif

      [aPrintServers replaceObjectAtIndex: i withObject: sTemp];//put back string into array for display in comboBox

#ifdef bDoDebug
      NSLog(@"aPrintServer: %@\n", [aPrintServers objectAtIndex: i]);
#endif

    

    [comboPrintServer removeAllItems];//reset combo box
    [comboPrintServer addItemsWithObjectValues:aPrintServers];
    [comboPrintServer setNumberOfVisibleItems:aPrintServers.count];
    [comboPrintServer selectItemAtIndex:0];

#ifdef bDoDebug
    NSLog(@"comboPrintServer reloaded with new values.");
#endif


//release memory we used for LdapTask
    [sLdapQueryCommand release];
    [aLdapQueryArgs release];
    [sLdapOutput release];

    [fhLdapTask release];

    [pipeLdapTask release];
//    [tskLdapTask release];//strangely can not be explicitely released, might be autorelease anyway
//    [mdLdapTask release];//strangely can not be explicitely released, might be autorelease anyway

    [sTemp release];

    

【参考方案7】：

我自己遇到过这样的例子：仅按组件分隔字符串是不够的，许多任务，例如 1) 将令牌分类为类型 2) 添加新令牌 3) 分隔字符串自定义闭包，例如“”和“”之间的所有单词对于任何此类要求，我发现 Parse Kit 可以救命。

我用它成功地解析了 .PGN（prtable 游戏符号）文件，它非常快速且精简。

【参考方案8】：

如果您希望将字符串标记为搜索词，同时保留“引用的短语”，这里有一个 NSString 类别，它尊重各种类型的引用对：""''‘’“”

用法：

NSArray *terms = [@"This is my \"search phrase\" I want to split" searchTerms];
// results in: ["This", "is", "my", "search phrase", "I", "want", "to", "split"]

代码：

@interface NSString (Search)
- (NSArray *)searchTerms;
@end

@implementation NSString (Search)

- (NSArray *)searchTerms 

    // Strip whitespace and setup scanner
    NSCharacterSet *whitespace = [NSCharacterSet whitespaceAndNewlineCharacterSet];
    NSString *searchString = [self stringByTrimmingCharactersInSet:whitespace];
    NSScanner *scanner = [NSScanner scannerWithString:searchString];
    [scanner setCharactersToBeSkipped:nil]; // we'll handle whitespace ourselves

    // A few types of quote pairs to check
    NSDictionary *quotePairs = @@"\"": @"\"",
                                 @"'": @"'",
                                 @"\u2018": @"\u2019",
                                 @"\u201C": @"\u201D";

    // Scan
    NSMutableArray *results = [[NSMutableArray alloc] init];
    NSString *substring = nil;
    while (scanner.scanLocation < searchString.length) 
        // Check for quote at beginning of string
        unichar unicharacter = [self characterAtIndex:scanner.scanLocation];
        NSString *startQuote = [NSString stringWithFormat:@"%C", unicharacter];
        NSString *endQuote = [quotePairs objectForKey:startQuote];
        if (endQuote != nil)  // if it's a valid start quote we'll have an end quote
            // Scan quoted phrase into substring (skipping start & end quotes)
            [scanner scanString:startQuote intoString:nil];
            [scanner scanUpToString:endQuote intoString:&substring];
            [scanner scanString:endQuote intoString:nil];
         else 
            // Single word that is non-quoted
            [scanner scanUpToCharactersFromSet:whitespace intoString:&substring];
        
        // Process and add the substring to results
        if (substring) 
            substring = [substring stringByTrimmingCharactersInSet:whitespace];
            if (substring.length) [results addObject:substring];
        
        // Skip to next word
        [scanner scanCharactersFromSet:whitespace intoString:nil];
    

    // Return non-mutable array
    return results.copy;



@end

【参考方案9】：

如果您正在寻找拆分字符串（单词、段落、字符、句子和行）的语言特征，请使用字符串枚举：

NSString * string = @" \n word1!    word2,%$?'/word3.word4   ";

[string enumerateSubstringsInRange:NSMakeRange(0, string.length)
                           options:NSStringEnumerationByWords
                        usingBlock:
 ^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) 
     NSLog(@"Substring: '%@'", substring);
 ];

 // Logs:
 // Substring: 'word1'
 // Substring: 'word2'
 // Substring: 'word3'
 // Substring: 'word4' 

此 api 可与空格不总是分隔符的其他语言（例如日语）一起使用。同样使用NSStringEnumerationByComposedCharacterSequences 是枚举字符的正确方法，因为许多非西方字符的长度超过一个字节。

【讨论】：

从ios12开始，也可以考虑NLTokenizer(developer.apple.com/documentation/naturallanguage/…)