在Objective-C中,对于分词/拆分NSString的最佳方法是什么?
在这里找到答案。
NSString *string = @"oop:ack:bork:greeble:ponies";
NSArray *chunks = [string componentsSeparatedByString: @":"];
大家都提到了componentsSeparatedByString:
,但是你也可以使用 CFStringTokenizer
(记住NSString
和CFString
是可互换的),它也可以对自然语言进行分词(比如中文/日文不会在空格上拆分单词)。
enumerateLinesUsingBlock:
和 enumerateSubstringsInRange:options:usingBlock:
,后者是基于块的CFStringTokenizer版本。具体信息请参考这里:http://developer.apple.com/mac/library/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/Reference/NSString.html#//apple_ref/occ/instm/NSString/enumerateLinesUsingBlock: 和 http://developer.apple.com/mac/library/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/Reference/NSString.html#//apple_ref/occ/instm/NSString/enumerateSubstringsInRange:options:usingBlock:。 - Peter Hoseyenumerate
方法也适用于 iOS 4 及以后的版本。 - bugloaf如果你只想拆分一个字符串,请使用 -[NSString componentsSeparatedByString:]
方法。对于更复杂的分词,可以使用 NSScanner 类。
如果只需要使用分隔符字符(如“:”)对字符串进行简单拆分,则使用ParseKit肯定过于复杂。但是,对于复杂的标记化需求,ParseKit非常强大/灵活。
还可以参见ParseKit标记化文档。
componentsSeparatedByCharactersInSet
。NSCharacterSet有一些方便的预制集合,例如whitespaceCharacterSet
和illegalCharacterSet
。它还有用于Unicode范围的初始化程序。// 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 charSet 中的多个成员,将产生空字符串,因此您可能需要测试长度小于1。
""
''
‘’
“”
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
如果您正在寻找将字符串的语言特征(单词、段落、字符、句子和行)分割开来的方法,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'
这个API可以处理其他语言中不一定以空格为分隔符的情况(例如日语)。而使用NSStringEnumerationByComposedCharacterSequences
是正确的枚举字符的方式,因为许多非西方字符超过一个字节长。
我成功地使用它来解析.PGN(便携式游戏注释)文件,速度非常快且轻巧。
我曾经遇到这样一个情况,需要在LDAP查询(ldapsearch)的控制台输出中进行拆分。首先设置并执行NSTask(我在这里找到了一个很好的代码示例:从Cocoa应用程序执行终端命令)。但是,我必须拆分和解析输出,以便仅提取Ldap查询输出中的打印服务器名称。不幸的是,这是相当繁琐的字符串操作,如果我们使用简单的C数组操作来操作C-strings/arrays,则不会有任何问题。因此,这是我的使用Cocoa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://dev59.com/kHRC5IYBdhLWcg3wFdFx 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];
}
}
[anArray componentsJoinedByString:@":"];
。 - Ivan VučicacomponentsSeparatedByCharactersInSet
。请看下面的答案。 - Wienke