I have a NSString formatted like this:
"Hello world 12 looking for some 56"
I want to find all instances of numbers separated by whitespace and place them in an NSArray. I dont want to remove the numbers though.
Whats the best way of achieving this?
This is a solution using regular expression as suggested in the comment.
NSString *string = #"Hello world 12 looking for some 56";
NSRegularExpression *expression = [NSRegularExpression regularExpressionWithPattern:#"\\b\\d+" options:nil error:nil];
NSArray *matches = [expression matchesInString:string options:nil range:(NSMakeRange(0, string.length))];
NSMutableArray *result = [[NSMutableArray alloc] init];
for (NSTextCheckingResult *match in matches) {
[result addObject:[string substringWithRange:match.range]];
}
NSLog(#"%#", result);
First make an array using NSString's componentsSeparatedByString method and take reference to this SO question. Then iterate the array and refer to this SO question to check if an array element is number: Checking if NSString is Integer.
I don't know where you are looking to do perform this action because it may not be fast (such as if it's being called in a table cell it may be choppy) based upon the string size.
Code:
+ (NSArray *)getNumbersFromString:(NSString *)str {
NSMutableArray *retVal = [NSMutableArray array];
NSCharacterSet *numericSet = [NSCharacterSet decimalDigitCharacterSet];
NSString *placeholder = #"";
unichar currentChar;
for (int i = [str length] - 1; i >= 0; i--) {
currentChar = [str characterAtIndex:i];
if ([numericSet characterIsMember:currentChar]) {
placeholder = [placeholder stringByAppendingString:
[NSString stringWithCharacters:¤tChar
length:[placeholder length]+1];
} else {
if ([placeholder length] > 0) [retVal addObject:[placeholder intValue]];
else placeholder = #"";
return [retVal copy];
}
To explain what is happening above, essentially I am,
going through every character until I find a number
adding that number including any numbers after to a string
once it finds a number it adds it to an array
Hope this helps please ask for clarification if needed
Related
I am trying to parse a set of words that contain -- first greek letters, then english letters. This would be easy if there was a delimiter between the sets.That is what I've built so far..
- (void)loadWordFileToArray:(NSBundle *)bundle {
NSLog(#"loadWordFileToArray");
if (bundle != nil) {
NSString *path = [bundle pathForResource:#"alfa" ofType:#"txt"];
//pull the content from the file into memory
NSData* data = [NSData dataWithContentsOfFile:path];
//convert the bytes from the file into a string
NSString* string = [[NSString alloc] initWithBytes:[data bytes]
length:[data length]
encoding:NSUTF8StringEncoding];
//split the string around newline characters to create an array
NSString* delimiter = #"\n";
incomingWords = [string componentsSeparatedByString:delimiter];
NSLog(#"incomingWords count: %lu", (unsigned long)incomingWords.count);
}
}
-(void)parseWordArray{
NSLog(#"parseWordArray");
NSString *seperator = #" = ";
int i = 0;
for (i=0; i < incomingWords.count; i++) {
NSString *incomingString = [incomingWords objectAtIndex:i];
NSScanner *scanner = [NSScanner localizedScannerWithString: incomingString];
NSString *firstString;
NSString *secondString;
NSInteger scanPosition;
[scanner scanUpToString:seperator intoString:&firstString];
scanPosition = [scanner scanLocation];
secondString = [[scanner string] substringFromIndex:scanPosition+[seperator length]];
// NSLog(#"greek: %#", firstString);
// NSLog(#"english: %#", secondString);
[outgoingWords insertObject:[NSMutableArray arrayWithObjects:#"greek", firstString, #"english",secondString,#"category", #"", nil] atIndex:0];
[englishWords insertObject:[NSMutableArray arrayWithObjects:secondString,nil] atIndex:0];
}
}
But I cannot count on there being delimiters.
I have looked at this question. I want something similar. This would be: grab the characters in the string until an english letter is found. Then take the first group to one new string, and all the characters after to a second new string.
I only have to run this a few times, so optimization is not my highest priority.. Any help would be appreciated..
EDIT:
I've changed my code as shown below to make use of NSLinguisticTagger. This works, but is this the best way? Note that the interpretation for english characters is -- for some reason "und"...
The incoming string is: άγαλμα, το statue, only the last 6 characters are in english.
int j = 0;
for (j=0; j<incomingString.length; j++) {
NSString *language = [tagger tagAtIndex:j scheme:NSLinguisticTagSchemeLanguage tokenRange:NULL sentenceRange:NULL];
if ([language isEqual: #"und"]) {
NSLog(#"j is: %i", j);
int k = 0;
for (k=0; k<j; k++) {
NSRange range = NSMakeRange (0, k);
NSString *tempString = [incomingString substringWithRange:range ];
NSLog (#"tempString: %#", tempString);
}
return;
}
NSLog (#"Language: %#", language);
}
Alright so what you could do is use NSLinguisticTagger to find out the language of the word (or letter) and if the language has changed then you know where to split the string. You can use NSLinguisticTagger like this:
NSArray *tagschemes = #[NSLinguisticTagSchemeLanguage];
NSLinguisticTagger *tagger = [[NSLinguisticTagger alloc] initWithTagSchemes:tagschemes options: NSLinguisticTagPunctuation | NSLinguisticTaggerOmitWhitespace];
[tagger setString:#"This is my string in English."];
NSString *language = [tagger tagAtIndex:0 scheme:NSLinguisticTagSchemeLanguage tokenRange:NULL sentenceRange:NULL];
//Loop through each index of the string's characters and check the language as above.
//If it has changed then you can assume the language has changed.
Alternatively you can use NSSpellChecker's requestCheckingOfString to get teh dominant language in a range of characters:
NSSpellChecker *spellChecker = [NSSpellChecker sharedSpellChecker];
[spellChecker setAutomaticallyIdentifiesLanguages:YES];
NSString *spellCheckText = #"Guten Herr Mustermann. Dies ist ein deutscher Text. Bitte löschen Sie diesen nicht.";
[spellChecker requestCheckingOfString:spellCheckText
range:(NSRange){0, [spellCheckText length]}
types:NSTextCheckingTypeOrthography
options:nil
inSpellDocumentWithTag:0
completionHandler:^(NSInteger sequenceNumber, NSArray *results, NSOrthography *orthography, NSInteger wordCount) {
NSLog(#"dominant language = %#", orthography.dominantLanguage);
}];
This answer has information on how to detect the language of an NSString.
Allow me to introduce two good friends of mine.
NSCharacterSet and NSRegularExpression.
Along with them, normalization. (In Unicode terms)
First, you should normalize strings before analyzing them against a character set.
You will need to look at the choices, but normalizing to all composed forms is the way I would go.
This means an accented character is one instead of two or more.
It simplifies the number of things to compare.
Next, you can easily build your own NSCharacterSet objects from strings (loaded from files even) to use to test set membership.
Lastly, regular expressions can achieve the same thing with Unicode Property Names as classes or categories of characters. Regular expressions could be more terse but more expressive.
I want to split NSString into array with fixed-length parts. How can i do this?
I searched about it, but i only find componentSeparatedByString method, but nothing more. It's also can be done manually, but is there a faster way to do this ?
Depends what you mean by "faster" - if it is processor performance you refer to, I'd guess that it is hard to beat substringWithRange:, but for robust, easy coding of a problem like this, regular expressions can actually come in quite handy.
Here's one that can be used to divide a string into 10-char chunks, allowing the last chunk to be of less than 10 chars:
NSString *pattern = #".{1,10}";
Unfortunately, the Cocoa implementation of the regex machinery is less elegant, but simple enough to use:
NSString *string = #"I want to split NSString into array with fixed-length parts. How can i do this?";
NSError *error = NULL;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern: pattern options: 0 error: &error];
NSArray *matches = [regex matchesInString:string options:0 range:NSMakeRange(0, [string length])];
NSMutableArray *result = [NSMutableArray array];
for (NSTextCheckingResult *match in matches) {
[result addObject: [string substringWithRange: match.range]];
}
Break the string into a sequence of NSRanges and then try using NSString's substringWithRange: method.
You can split a string in different ways.
One way is to split by spaces(or any character):
NSString *string = #"Hello World Obj C is Awesome";
NSArray *words = [string componentsSeparatedByString:#" "];
You can also split at exact points in a string:
NSString *word = [string substringWithRange:NSMakeRange(startPoint, FIXED_LENGTH)];
Simply put it in a loop for a fixed length and save to Mutable Array:
NSMutableArray *words = [NSMutableArray array];
for (int i = 0; i < [string length]; i++) {
NSString *word = [string substringWithRange:NSMakeRange(i, FIXED_LENGTH)]; //you may want to make #define
[array addObject:word];
}
Hope this helps.
I have a block of text (a newspaper article if it's of any relevance) was wondering if there is a way to extract all sentences containing a particular keyword in objective-c? I've been looking a bit at ParseKit but aren't having much luck!
You can enumerate sentences using native NSString methods like this...
NSString *string = #"your text";
NSMutableArray *sentences = [NSMutableArray array];
[string enumerateSubstringsInRange:NSMakeRange(0, string.length)
options:NSStringEnumerationBySentences
usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) {
//check that this sentence has the string you are looking for
NSRange range = [substring rangeOfString:#"The text you are looking for"];
if (range.location != NSNotFound) {
[sentences addObject:substring];
}
}];
for (NSString *sentence in sentences) {
NSLog(#"%#", sentence);
}
At the end you will have an array of sentences all containing the text you were looking for.
Edit: As noted in the comments there are some inherit weaknesses with my solution as it requires a perfectly formatted sentence where period + space is only used when actually ending sentences... I'll leave it in here as it could be viable for people sorting a text with another (known) separator.
Here's another way of achieving what you want:
NSString *wordYouAreLookingFor = #"happy";
NSArray *arrayOfSentences = [aString componentsSeparatedByString:#". "]; // get the single sentences
NSMutableArray *sentencesWithMatchingWord = [[NSMutableArray alloc] init];
for (NSString *singleSentence in arrayOfSentences) {
NSInteger originalSize = [singleSentence length];
NSString *possibleNewString = [singleSentence stringByReplacingOccurrencesOfString:wordYouAreLookingFor withString:#""];
if (originalSize != [possibleNewString length]) {
[sentencesWithMatchingWord addObject:singleSentence];
}
}
Given a string, I need to obtain a count of each word that appears in that string. To do so, I extracted the string into an array, by word, and searched that way, but I have the feeling that searching the string directly is more optimal. Below is the code that I originally wrote to solve the problem. I'm up for suggestions on better solutions though.
NSMutableDictionary *sets = [[NSMutableDictionary alloc] init];
NSString *paragraph = [[NSString alloc] initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"text" ofType:#"txt"] encoding:NSUTF8StringEncoding error:NULL];
NSMutableArray *words = [[[paragraph lowercaseString] componentsSeparatedByString:#" "] mutableCopy];
while (words.count) {
NSMutableIndexSet *indexSet = [[NSMutableIndexSet alloc] init];
NSString *search = [words objectAtIndex:0];
for (unsigned i = 0; i < words.count; i++) {
if ([[words objectAtIndex:i] isEqualToString:search]) {
[indexSet addIndex:i];
}
}
[sets setObject:[NSNumber numberWithInt:indexSet.count] forKey:search];
[words removeObjectsAtIndexes:indexSet];
}
NSLog(#"%#", sets);
Example:
Starting string:
"This is a test. This is only a test."
Results:
"This" - 2
"is" - 2
"a" - 2
"test" - 2
"only" - 1
This is exactly what an NSCountedSet is for.
You need to break the string apart into words (which iOS is nice enough to give us a function for so that we don't have to worry about punctuation) and just add each of them to the counted set, which keeps track of the number of times each object appears in the set:
NSString *string = #"This is a test. This is only a test.";
NSCountedSet *countedSet = [NSCountedSet new];
[string enumerateSubstringsInRange:NSMakeRange(0, [string length])
options:NSStringEnumerationByWords | NSStringEnumerationLocalized
usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop){
// This block is called once for each word in the string.
[countedSet addObject:substring];
// If you want to ignore case, so that "this" and "This"
// are counted the same, use this line instead to convert
// each word to lowercase first:
// [countedSet addObject:[substring lowercaseString]];
}];
NSLog(#"%#", countedSet);
// Results: 2012-11-13 14:01:10.567 Testing App[35767:fb03]
// <NSCountedSet: 0x885df70> (a [2], only [1], test [2], This [2], is [2])
If I had to guess, I would say NSRegularExpression for that. Like this:
NSUInteger numberOfMatches = [regex numberOfMatchesInString:string
options:0
range:NSMakeRange(0, [string length])];
That snippet was taken from here.
Edit 1.0:
Based on what Sir Till said:
NSString *string = #"This is a test, so it is a test";
NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];
NSArray *arrayOfWords = [string componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
for (NSString *word in arrayOfWords)
{
if ([dictionary objectForKey:word])
{
NSNumber *numberOfOccurences = [dictionary objectForKey:word];
NSNumber *increment = [NSNumber numberWithInt:(1 + [numberOfOccurences intValue])];
[dictionary setValue:increment forKey:word];
}
else
{
[dictionary setValue:[NSNumber numberWithInt:1] forKey:word];
}
}
You should be careful with:
Punctuation signs. (near other words)
UpperCase words vs lowerCase words.
I think that's really bad idea that you trying to search a words among the long paragraph with a loop. You should use a regular expression to do that! I know it's not easy at first time to learn it but it's really worth to know it! Take look at this case Use regular expression to find/replace substring in NSString
I am trying to replace all characters except last 4 in a String with *'s.
In objective-c there is a method in NSString class replaceStringWithCharactersInRange: withString: where I would give it range (0,[string length]-4) ) with string #"*". This is what it does: 123456789ABCD is modified to *ABCD while I am looking to make ********ABCD.
I understand that it replaced range I specified with string object. How to accomplish this ?
NSError *error;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:#"\\d" options:NSRegularExpressionCaseInsensitive error:&error];
NSString *newString = [regex stringByReplacingMatchesInString:string options:0 range:NSMakeRange(0, [string length]) withTemplate:#"*"];
This looks like a simple problem... get the first part string and return it with the last four characters appended to it.
Here is a function that returns the needed string :
-(NSString *)neededStringWithString:(NSString *)aString {
// if the string has less than or 4 characters, return nil
if([aString length] <= 4) {
return nil;
}
NSUInteger countOfCharToReplace = [aString length] - 4;
NSString *firstPart = #"*";
while(--countOfCharToReplace) {
firstPart = [firstPart stringByAppendingString:#"*"];
}
// range for the last four
NSRange lastFourRange = NSMakeRange([aString length] - 4, 4);
// return the combined string
return [firstPart stringByAppendingString:
[aString substringWithRange:lastFourRange]];
}
The most unintuitive part in Cocoa is creating the repeating stars without some kind of awkward looping. stringByPaddingToLength:withString:startingAtIndex: allows you to create a repeating string of any length you like, so once you have that, here's a simple solution:
NSInteger starUpTo = [string length] - 4;
if (starUpTo > 0) {
NSString *stars = [#"" stringByPaddingToLength:starUpTo withString:#"*" startingAtIndex:0];
return [string stringByReplacingCharactersInRange:NSMakeRange(0, starUpTo) withString:stars];
} else {
return string;
}
I'm not sure why the accepted answer was accepted, since it only works if everything but last 4 is a digit. Here's a simple way:
NSMutableString * str1 = [[NSMutableString alloc]initWithString:#"1234567890ABCD"];
NSRange r = NSMakeRange(0, [str1 length] - 4);
[str1 replaceCharactersInRange:r withString:[[NSString string] stringByPaddingToLength:r.length withString:#"*" startingAtIndex:0]];
NSLog(#"%#",str1);
You could use [theString substringToIndex:[theString length]-4] to get the first part of the string and then combine [theString length]-4 *'s with the second part. Perhaps their is an easier way to do this..
NSMutableString * str1 = [[NSMutableString alloc]initWithString:#"1234567890ABCD"];
[str1 replaceCharactersInRange:NSMakeRange(0, [str1 length] - 4) withString:#"*"];
NSLog(#"%#",str1);
it works
The regexp didn't work on iOS7, but perhaps this helps:
- (NSString *)encryptString:(NSString *)pass {
NSMutableString *secret = [NSMutableString new];
for (int i=0; i<[pass length]; i++) {
[secret appendString:#"*"];
}
return secret;
}
In your case you should stop replacing the last 4 characters. Bit crude, but gets the job done