Does anyone know a nice efficient way of finding a string within a string (if it exists) in objective c for iPhone Development, I need to find the part of the string in between two words, e.g. here I need to find the co2 rating number in the string, where z is the value I'm looking for ...
xxxxxco_2zendxxxxxxx
Ideally, I'd use a regular expression for this, probably something like co_2(.*?)end, so I'd take a look at RegexKitLite as stimms suggests.
If that is not suitable, you could extract the string you're looking for with something like this:
NSString* src = #"xxxxxco_2zendxxxxxxx";
NSRange startMarker = [src rangeOfString:#"co_2"];
if (startMarker.location != NSNotFound) {
NSScanner* scanner = [NSScanner scannerWithString:src];
[scanner setScanLocation:startMarker.location + startMarker.length];
NSString* co2Value = #"";
[scanner scanUpToString:#"end" intoString:&co2Value];
NSLog(#"co_2 value is %#", co2Value);
} else {
NSLog(#"co_2 marker not found");
}
Here we look for #"co_2", failing if it's not found, then use an NSScanner to grab everything from just after that string to the next occurrence of #"end". Note that if #"end" is missing this code will silently grab the rest of the string.
This might be of interest to you (in particular the rangeOfString function):
(NSRange)rangeOfString:(NSString *)aString
Unfortunately Cocoa doesn't have any built-in RegEx support..
String matching is a well explored domain especially for algorithms dealing with genetic material. You could check out the Art of Computer programming for 10x more than you ever wanted to know about string matching.
Most of that is overkill and you would be fine using a regular expression. Check out http://regexkit.sourceforge.net/RegexKitLite/ a regex library which runs on the iphone.
Related
The following example program outputs the same, but the program does not work correctly.
NSDirectoryEnumerator *directoryEnumerator = [[NSFileManager defaultManager]
enumeratorAtPath:kDocdir];
for (NSString *pathi in directoryEnumerator)
{
NSString *fileName_Manager = [pathi lastPathComponent];
NSLog(#"fileName_Manager = %#",fileName_Manager);
Artist *name_Databse = [self.fetchedResultsController
objectAtIndexPath:IndexPath];
NSLog(#"name_Databse = %#",name_Databse.name);
if ([fileName_Manager isEqualToString:name_Databse.name]) {
NSLog(#"Same Name");
}else{
NSLog(#"Different Name");
}
}
Outputs:
2013-04-25 15:37:43.256 Player[36436:907] fileName_Manager = alizée - mèxico - final j'en
2013-04-25 15:37:43.272 Player[36436:907] name_Databse = alizée - mèxico - final j'en
2013-04-25 15:37:44.107 Player[36436:907] Different Name
does not work correctly when special characters in names. Why is this happening?
Thanks ...
have the same problem here:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"name == %#",[pathi lastPathComponent]];
How do I make an edit here?
The documentation for isEqualToString: suggests you might have a problem:
The comparison uses the canonical representation of strings, which for
a particular string is the length of the string plus the Unicode
characters that make up the string. When this method compares two
strings, if the individual Unicodes are the same, then the strings are
equal, regardless of the backing store. “Literal” when applied to
string comparison means that various Unicode decomposition rules are
not applied and Unicode characters are individually compared. So,
for instance, “Ö” represented as the composed character sequence “O”
and umlaut would not compare equal to “Ö” represented as one Unicode
character.
Try using (NSOrderedSame == [string1 localizedCompare:string2])
Also, if you haven't already, look into the Apple sample code 'International Mountains' which deals with numerous localization issues.
Have you tried converting both strings to UTF-8 and then do the comparison? I don't know if that works, it's just an idea.
I need to display subscripts and superscripts (only arabic numerals) within a UILabel. The data is taken from an XML file. Here is the snippet of XML file:
<text><![CDATA[Hello World X\u00B2 World Hello]]></text>
Its supposed to display X2 (2 as superscript). When I read the string from the NSXMLParser and display it in the UILabel, it displays it as X\u00B2. Any ideas on how to make it work?
I think you can do something like this, assuming the CDATA contents have been read into an NSString and passed into this function:
-(NSString *)removeUnicodeEscapes:(NSString *)stringWithUnicodeEscapes {
unichar codeValue;
NSMutableString *result = [stringWithUnicodeEscapes mutableCopy];
NSRange unicodeLocation = [result rangeOfString:#"\\u"];
while (unicodeLocation.location != NSNotFound) {
// Get the 4-character hex code
NSRange charCodeRange = NSMakeRange(unicodeLocation.location + 2, 4);
NSString *charCode = [result substringWithRange:charCodeRange];
[[NSScanner scannerWithString:charCode] scanHexInt:&codeValue];
// Convert it to an NSString and replace in original string
NSString *unicodeChar = [NSString stringWithFormat:%C", codeValue];
NSRange replacementRange = NSMakeRange(unicodeLocation.location, 6);
[result replaceCharactersInRange:replacementRange withString:unicodeChar];
unicodeLocation = [result rangeOfString:#"\\u"];
}
return result;
}
I haven't had a chance to try this out, but I think the basic approach would work
\u00B2 is not any sort of XML encoding for characters. Apparently your data source has defined their own encoding scheme (which, frankly, is pretty stupid as XML is capable of encoding these directly, using entities outside of CDATA blocks).
In any case, you'll have to write your own parser that handles \u#### and converts that to the correct character.
I asked the question to my colleague and he gave me a nice and simple workaround. Am describing it here, in case others also get stuck at this.
Firstly goto this link. It has a list of all subscripts and superscripts. For example, in my case, I clicked on "superscript 0". In the following HTML page detailing "superscript 0", goto "Java Data" section and copy the "⁰". You can either place this directly in XML or write a simple regex in obj-c to replace \u00B2 with "⁰". And you will get nice X⁰. Do the same fro anyother superscript or subscript that you might want to display.
I need a (quick and dirty) solution to basically detect if a certain NSString is a 'real' word, that is, if it's in the dictionary. So basically, a very simplistic spell checker. Does anyone know of any way to do this? Basically I either need a file containing all words in the English dictionary (which I've searched for, but to no avail), or a way to interface with the iPhones spell checking service. Of course I would like to interface with the iPhones spell check service in a similar way to NSSpellChecker on OSX so my app will work with other languages, but at this point I'll take what I can get.
Lastly, here's some pseudo-code to better illustrate my needs:
-(BOOL)isDictionaryWord:(NSString*)word; //returns TRUE when word=#"greetings". returns FALSE when word=#"slkfjsdkl";
Use UITextChecker instead. The code below might not be perfect but should give you a good idea.
-(BOOL)isDictionaryWord:(NSString*)word {
UITextChecker *checker = [[UITextChecker alloc] init];
NSLocale *currentLocale = [NSLocale currentLocale];
NSString *currentLanguage = [currentLocale objectForKey:NSLocaleLanguageCode];
NSRange searchRange = NSMakeRange(0, [word length]);
NSRange misspelledRange = [checker rangeOfMisspelledWordInString:word range:searchRange startingAt:0 wrap:NO language:currentLanguage];
return misspelledRange.location == NSNotFound;
}
You can make UITextChecker work accurately without needing to add a new dictionary.
I use a two-step process because I need the first step to be fast (but not accurate). You may only need step two which is the accurate check. Note this makes use of the UITextChecker's completionsForPartialWordRange function which is why it's more accurate than the MisspelledWord function.
//Step one: I quickly check to see if a combination of letters passes the spell check. This is not that accurate but it's very fast so I can quickly exclude lots of letter combinations (brute force approach).
UITextChecker *checker;
NSString *wordToCheck = #"whatever"; // The combination of letters you wish to check
// Set the range to the length of the word
NSRange range = NSMakeRange(0, wordToCheck.length - 1);
NSRange misspelledRange = [checker rangeOfMisspelledWordInString:wordToCheck range: range startingAt:0 wrap:NO language: #"en_US"];
BOOL isRealWord = misspelledRange.location == NSNotFound;
// Call step two, to confirm that this is a real word
if (isRealWord) {
isRealWord = [self isRealWordOK:wordToCheck];
}
return isRealWord; // if true then we found a real word, if not move to next combination of letters
// Step Two: Extra check to make sure the word is really a real word. returns true if we have a real word.
-(BOOL)isRealWordOK:(NSString *)wordToCheck {
// we dont want to use any words that the lexicon has learned.
if ([UITextChecker hasLearnedWord:wordToCheck]) {
return NO;
}
// now we are going to use the word completion function to see if this word really exists, by removing the final letter and then asking auto complete to complete the word, then look through all the results and if its not found then its not a real word. Note the auto complete is very acurate unlike the spell checker.
NSRange range = NSMakeRange(0, wordToCheck.length - 1);
NSArray *guesses = [checker completionsForPartialWordRange:range inString:wordToCheck language:#"en_US"];
// confirm that the word is found in the auto-complete list
for (NSString *guess in guesses) {
if ([guess isEqualToString:wordToCheck]) {
// we found the word in the auto complete list so it's real :-)
return YES;
}
}
// if we get to here then it's not a real word :-(
NSLog(#"Word not found in second dictionary check:%#",wordToCheck);
return NO;
}
#"/News/some news text/"
#"/News/some other news text/"
#"/About/Some about text/"
#"/Abcdefg/Some abcdefg text/some more abcdefg text"
How do I cut out the first part of the strings, so that I end up with the following strings?
#"/News/"
#"/News/"
#"/About/"
#"/Abcdefg/"
Use componentsSeparatedByString: to break the string up:
NSArray *components=[string componentsSeparatedByString:#"/"];
if ([components count]>=2) {
// Text after the first slash is second item in the array
return [NSString stringWithFormat:#"/%#/",[components objectAtIndex:1]];
} else {
return nil; // Up to you what happens in this situation
}
If these are pathnames, you may want to look into the path-related methods of NSString, such as pathComponents and pathByDeletingLastPathComponent.
While it's pretty unlikely that the path separator is ever going to change, it's nonetheless a good habit to not rely on such things and use dedicated path-manipulation methods in preference to assuming that the path separator will be a certain character.
EDIT from the year 2013: Or use URLs (more specifically, NS/CFURL objects), which Apple has made pretty clear are the proper way to refer to files from now on, and are necessary for some tasks in a sandbox.
I have an NSString with a number of sentences, and I'd like to split it into an NSArray of sentences. Has anybody solved this problem before? I found enumerateSubstringsInRange:options:usingBlock: which is able to do it, but it looks like it isn't available on the iPhone (Snow Leopard only). I thought about splitting the string based on periods, but that doesn't seem very robust.
So far my best option seems to be to use RegexKitLite to regex it into an array of sentences. Solutions?
Use CFStringTokenizer. You'll want to create the tokenizer with the kCFStringTokenizerUnitSentence option.
I would use a scanner for it,
NSScanner *sherLock = [NSCanner scannerWithString:yourString]; // autoreleased
NSMutableArray *theArray = [NSMutableArray array]; // autoreleased
while( ![sherLock isAtEnd] ){
NSString *sentence = #"";
// . + a space, your sentences probably will have that, and you
// could try scanning for a newline \n but iam not sure your sentences
// are seperated by it
[sherLock scanUpToString:#". " inToString:&sentence];
[theArray addObject:sentence];
}
This should do it, there could be some little mistakes in it but this is how I would do it.
You should lookup NSScanner in the docs though.. you might come across a method that is
better for this situation.
I haven't used them for a while but I think you can do this with NSString, NSCharacterSet and NSScanner. You create a character set that holds end sentence punctuation and then call -[NSScanner scanUpToCharactersFromSet:intoString:]. Each Scan will suck out a sentence into a string and you keep calling the method until the scanner runs out of string.
Of course, the text has to be well punctuated.
How about:
NSArray *sentences = [string componentsSeparatedByString:#". "];
This will return an array("One","Two","Three") from a string "One. Two. Three."
NSArray *sentences = [astring componentsSeparatedByCharactersInSet:[NSCharacterSet punctuationCharacterSet] ];