I want to know a simple and fast way to determine if all characters in an NSString are the same.
For example:
NSString *string = "aaaaaaaaa"
=> return YES
NSString *string = "aaaaaaabb"
=> return NO
I know that I can achieve it by using a loop but my NSString is long so I prefer a shorter and simpler way.
you can use this, replace first character with null and check lenght:
-(BOOL)sameCharsInString:(NSString *)str{
if ([str length] == 0 ) return NO;
return [[str stringByReplacingOccurrencesOfString:[str substringToIndex:1] withString:#""] length] == 0 ? YES : NO;
}
Here are two possibilities that fail as quickly as possible and don't (explicitly) create copies of the original string, which should be advantageous since you said the string was large.
First, use NSScanner to repeatedly try to read the first character in the string. If the loop ends before the scanner has reached the end of the string, there are other characters present.
NSScanner * scanner = [NSScanner scannerWithString:s];
NSString * firstChar = [s substringWithRange:[s rangeOfComposedCharacterSequenceAtIndex:0]];
while( [scanner scanString:firstChar intoString:NULL] ) continue;
BOOL stringContainsOnlyOneCharacter = [scanner isAtEnd];
Regex is also a good tool for this problem, since "a character followed by any number of repetitions of that character" is in very simply expressed with a single back reference:
// Match one of any character at the start of the string,
// followed by any number of repetitions of that same character
// until the end of the string.
NSString * patt = #"^(.)\\1*$";
NSRegularExpression * regEx =
[NSRegularExpression regularExpressionWithPattern:patt
options:0
error:NULL];
NSArray * matches = [regEx matchesInString:s
options:0
range:(NSRange){0, [s length]}];
BOOL stringContainsOnlyOneCharacter = ([matches count] == 1);
Both these options correctly deal with multi-byte and composed characters; the regex version also does not require an explicit check for the empty string.
use this loop:
NSString *firstChar = [str substringWithRange:NSMakeRange(0, 1)];
for (int i = 1; i < [str length]; i++) {
NSString *ch = [str substringWithRange:NSMakeRange(i, 1)];
if(![ch isEqualToString:firstChar])
{
return NO;
}
}
return YES;
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 am new to Objective-C, so I am trying to split an String into an Array in this format:
NSString *str = #":49:DE:Bahnhofsstr:12:39:11";
NSArray *arr = [str componentsSeparatedByString:#":"];
I receive the following objects in arr:
[#"", #"49", #"DE", #"Bahnhofsstr", #"12", #"39", #"11"]
But I need it in this format:
[#"", #"49", #"DE", #"Bahnhofsstr:12:39:11"]
Anyone have any ideas?
You can use a regular expression. The one you want is this:
^([^:]*):([^:]*):([^:]*):(.*)$
The above matches three sequences of characters without colons in separated by colons and then a fourth group consisting of any kind of character. The ^ at the front and the $ at the end match the beginning and the end of the string respectively otherwise nonsense like 1:2:3:4:49:DE:Bahnhofsstr:12:39:11 would match because there is a match embedded in the string.
The parenthesis delimit capture groups which will be returned to you once the regular expression matching has been done. The first capture group is all the characters up to the first colon. The second capture group is all the characters between the first and second colons. The third capture group is all the characters between the second and third colons and the fourth capture group is all the characters after the third colon.
There is also a zeroth capture group which is the entire matching sequence.
Here's how to use this in Objective-C:
NSString* pattern = #"^([^:]*):([^:]*):([^:]*):(.*)$";
NSString* line = #":49:DE:Bahnhofsstr:12:39:11";
NSRegularExpression* regex = [NSRegularExpression regularExpressionWithPattern: pattern
options: 0
error: &error];
if (regex == nil)
{
NSLog(#"Invalid regular expression %#, %#", pattern, error);
}
else
{
NSArray* matches = [regex matchesInString: line
options: 0
range: NSMakeRange(0, [line length])];
if ([matches count] == 1)
{
// Should only be one match
NSTextCheckingResult* result = [matches objectAtIndex: 0];
NSMutableArray* captureGroups = [[NSMutableArray alloc] init];
// Omit capture group 0 because it will be the whole string
for (int i = 1 ; i < [result numberOfRanges] ; i++)
{
NSRange groupRange = [result rangeAtIndex: i];
NSString* captureGroup = [line substringWithRange: groupRange];
[captureGroups addObject: captureGroup];
}
NSLog(#"The fields are %#", captureGroups);
}
else
{
// match error
}
}
Regular expressions, as proposed by JeremyP, are an obvious solution to this sort of problem.
Some people don't like regexes, though, so another solution is to use NSScanner which is also made to scan strings and read the result into variables. Given that the delimiter is the same for all fields, it even lends itself to use a nice loop, reducing the tedious scanning code.
Here is an example:
NSString *str = #":49:DE:Bahnhofsstr:12:39:11";
const NSUInteger nFields = 4;
NSScanner *myScanner = [NSScanner scannerWithString: str];
NSMutableArray *arr = [NSMutableArray array];
for (NSUInteger i = 0; i < nFields - 1; i++) {
NSString *field;
// The BOOLs here really ought to be checked
BOOL found = [myScanner scanUpToString: #":" intoString: &field];
BOOL passedDelimiter = [myScanner scanString: #":" intoString: NULL];
[arr addObject: field ?: #"" ];
}
NSString *lastField = [[myScanner string] substringFromIndex:[myScanner scanLocation]];
[arr addObject: lastField];
That last line to read the remainder of the string is taken straight from the docs for NSScanner.
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
I have a string as shown below,
NSString * aString = #"This is the #substring1 and #subString2 I want";
How can I select only the text starting with '#' (and ends with a space), in this case 'subString1' and 'subString2'?
Note: Question was edited for clarity
You can do this using an NSScanner to split the string up. This code will loop through a string and fill an array with substrings.
NSString * aString = #"This is the #substring1 and #subString2 I want";
NSMutableArray *substrings = [NSMutableArray new];
NSScanner *scanner = [NSScanner scannerWithString:aString];
[scanner scanUpToString:#"#" intoString:nil]; // Scan all characters before #
while(![scanner isAtEnd]) {
NSString *substring = nil;
[scanner scanString:#"#" intoString:nil]; // Scan the # character
if([scanner scanUpToString:#" " intoString:&substring]) {
// If the space immediately followed the #, this will be skipped
[substrings addObject:substring];
}
[scanner scanUpToString:#"#" intoString:nil]; // Scan all characters before next #
}
// do something with substrings
[substrings release];
Here is how the code works:
Scan up to a #. If it isn't found, the scanner will be at the end of the string.
If the scanner is at the end of the string, we are done.
Scan the # character so that it isn't in the output.
Scan up to a space, with the characters that are scanned stored in substring. If either the # was the last character, or was immediately followed by a space, the method will return NO. Otherwise it will return YES.
If characters were scanned (the method returned YES), add substring to the substrings array.
GOTO 1
[aString substringWithRange:NSMakeRange(13, 10)]
would give you substring1
You can calculate the range using:
NSRange startRange = [aString rangeOfString:#"#"];
NSRange endRange = [original rangeOfString:#"1"];
NSRange searchRange = NSMakeRange(startRange.location , endRange.location);
[aString substringWithRange:searchRange]
would give you substring1
Read more:
Position of a character in a NSString or NSMutableString
and
http://iosdevelopertips.com/cocoa/nsrange-and-nsstring-objects.html
Pretty simple, easy to understand version avoiding NSRange stuff:
NSArray * words = [string componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
NSMutableArray * mutableWords = [NSMutableArray new];
for (NSString * word in words){
if ([word length] > 1 && [word characterAtIndex:0] == '#'){
NSString * editedWord = [word substringFromIndex:1];
[mutableWords addObject:editedWord];
}
}
Assuming that you are looking to find the first string that starts with a pound, and ends with a space, this might work. I don't have XCode in front of me, so forgive me if there's a syntax error or length off by 1 somewhere:
-(NSString *)StartsWithPound:(NSString *)str {
NSRange range = [str rangeOfString:#"#"];
if(range.length) {
NSRange rangeend = [str rangeOfString:#" " options:NSLiteralSearch range:NSMakeRange(range.location,[str length] - range.location - 1)];
if(rangeend.length) {
return [str substringWithRange:NSMakeRange(range.location,rangeend.location - range.location)];
}
else
{
return [str substringFromIndex:range.location];
}
}
else {
return #"";
}
}
Another simple solution:
NSRange hashtag = [aString rangeOfString:#"#"];
NSRange word = [[aString substringFromIndex:hashtag.location] rangeOfString:#" "];
NSString *hashtagWord = [aString substringWithRange:NSMakeRange(hashtag.location, word.location)];
This is what I'd do:
NSString *givenStringWithWhatYouNeed = #"What you want to look through";
NSArray *listOfWords = [givenStringWithWhatYouNeed componentsSeparatedByString:#" "];
for (NSString *word in listOfWords) {
if ([[word substringWithRange:NSMakeRange(0, 1)]isEqualToString:#"#"]) {
NSString *whatYouWant = [[word componentsSeparatedByString:#"#"]lastObject];
}
}
Then you can do what you need with the whatYouWant instances. If you want to know which string it is (if it's the substring 1 or 2), check the index of of word string in the listOfWords array.
I hope this helps.
A general and simple code to select all the words starting with "#" in a NSString is:
NSString * aString = #"This is the #substring1 and #subString2 ...";
NSMutableArray *selection=#[].mutableCopy;
while ([aString rangeOfString:#"#"].location != NSNotFound)
{
aString = [aString substringFromIndex:[aString rangeOfString:#"#"].location +1];
NSString *item=([aString rangeOfString:#" "].location != NSNotFound)?[aString substringToIndex:[aString rangeOfString:#" "].location]:aString;
[selection addObject:item];
}
if you still need the original string you can do a copy.
The inline conditional is used in case your selected item is the last word
I have an NSString (phone number) with some parenthesis and hyphens as some phone numbers are formatted. How would I remove all characters except numbers from the string?
Old question, but how about:
NSString *newString = [[origString componentsSeparatedByCharactersInSet:
[[NSCharacterSet decimalDigitCharacterSet] invertedSet]]
componentsJoinedByString:#""];
It explodes the source string on the set of non-digits, then reassembles them using an empty string separator. Not as efficient as picking through characters, but much more compact in code.
There's no need to use a regular expressions library as the other answers suggest -- the class you're after is called NSScanner. It's used as follows:
NSString *originalString = #"(123) 123123 abc";
NSMutableString *strippedString = [NSMutableString
stringWithCapacity:originalString.length];
NSScanner *scanner = [NSScanner scannerWithString:originalString];
NSCharacterSet *numbers = [NSCharacterSet
characterSetWithCharactersInString:#"0123456789"];
while ([scanner isAtEnd] == NO) {
NSString *buffer;
if ([scanner scanCharactersFromSet:numbers intoString:&buffer]) {
[strippedString appendString:buffer];
} else {
[scanner setScanLocation:([scanner scanLocation] + 1)];
}
}
NSLog(#"%#", strippedString); // "123123123"
EDIT: I've updated the code because the original was written off the top of my head and I figured it would be enough to point the people in the right direction. It seems that people are after code they can just copy-paste straight into their application.
I also agree that Michael Pelz-Sherman's solution is more appropriate than using NSScanner, so you might want to take a look at that.
The accepted answer is overkill for what is being asked. This is much simpler:
NSString *pureNumbers = [[phoneNumberString componentsSeparatedByCharactersInSet:[[NSCharacterSet decimalDigitCharacterSet] invertedSet]] componentsJoinedByString:#""];
This is great, but the code does not work for me on the iPhone 3.0 SDK.
If I define strippedString as you show here, I get a BAD ACCESS error when trying to print it after the scanCharactersFromSet:intoString call.
If I do it like so:
NSMutableString *strippedString = [NSMutableString stringWithCapacity:10];
I end up with an empty string, but the code doesn't crash.
I had to resort to good old C instead:
for (int i=0; i<[phoneNumber length]; i++) {
if (isdigit([phoneNumber characterAtIndex:i])) {
[strippedString appendFormat:#"%c",[phoneNumber characterAtIndex:i]];
}
}
Though this is an old question with working answers, I missed international format support. Based on the solution of simonobo, the altered character set includes a plus sign "+". International phone numbers are supported by this amendment as well.
NSString *condensedPhoneNumber = [[phoneNumber componentsSeparatedByCharactersInSet:
[[NSCharacterSet characterSetWithCharactersInString:#"+0123456789"]
invertedSet]]
componentsJoinedByString:#""];
The Swift expressions are
var phoneNumber = " +1 (234) 567-1000 "
var allowedCharactersSet = NSMutableCharacterSet.decimalDigitCharacterSet()
allowedCharactersSet.addCharactersInString("+")
var condensedPhoneNumber = phoneNumber.componentsSeparatedByCharactersInSet(allowedCharactersSet.invertedSet).joinWithSeparator("")
Which yields +12345671000 as a common international phone number format.
Here is the Swift version of this.
import UIKit
import Foundation
var phoneNumber = " 1 (888) 555-5551 "
var strippedPhoneNumber = "".join(phoneNumber.componentsSeparatedByCharactersInSet(NSCharacterSet.decimalDigitCharacterSet().invertedSet))
Swift version of the most popular answer:
var newString = join("", oldString.componentsSeparatedByCharactersInSet(NSCharacterSet.decimalDigitCharacterSet().invertedSet))
Edit: Syntax for Swift 2
let newString = oldString.componentsSeparatedByCharactersInSet(NSCharacterSet.decimalDigitCharacterSet().invertedSet).joinWithSeparator("")
Edit: Syntax for Swift 3
let newString = oldString.components(separatedBy: CharacterSet.decimalDigits.inverted).joined(separator: "")
Thanks for the example. It has only one thing missing the increment of the scanLocation in case one of the characters in originalString is not found inside the numbers CharacterSet object. I have added an else {} statement to fix this.
NSString *originalString = #"(123) 123123 abc";
NSMutableString *strippedString = [NSMutableString
stringWithCapacity:originalString.length];
NSScanner *scanner = [NSScanner scannerWithString:originalString];
NSCharacterSet *numbers = [NSCharacterSet
characterSetWithCharactersInString:#"0123456789"];
while ([scanner isAtEnd] == NO) {
NSString *buffer;
if ([scanner scanCharactersFromSet:numbers intoString:&buffer]) {
[strippedString appendString:buffer];
}
// --------- Add the following to get out of endless loop
else {
[scanner setScanLocation:([scanner scanLocation] + 1)];
}
// --------- End of addition
}
NSLog(#"%#", strippedString); // "123123123"
It Accept only mobile number
NSString * strippedNumber = [mobileNumber stringByReplacingOccurrencesOfString:#"[^0-9]" withString:#"" options:NSRegularExpressionSearch range:NSMakeRange(0, [mobileNumber length])];
It might be worth noting that the accepted componentsSeparatedByCharactersInSet: and componentsJoinedByString:-based answer is not a memory-efficient solution. It allocates memory for the character set, for an array and for a new string. Even if these are only temporary allocations, processing lots of strings this way can quickly fill the memory.
A memory friendlier approach would be to operate on a mutable copy of the string in place. In a category over NSString:
-(NSString *)stringWithNonDigitsRemoved {
static NSCharacterSet *decimalDigits;
if (!decimalDigits) {
decimalDigits = [NSCharacterSet decimalDigitCharacterSet];
}
NSMutableString *stringWithNonDigitsRemoved = [self mutableCopy];
for (CFIndex index = 0; index < stringWithNonDigitsRemoved.length; ++index) {
unichar c = [stringWithNonDigitsRemoved characterAtIndex: index];
if (![decimalDigits characterIsMember: c]) {
[stringWithNonDigitsRemoved deleteCharactersInRange: NSMakeRange(index, 1)];
index -= 1;
}
}
return [stringWithNonDigitsRemoved copy];
}
Profiling the two approaches have shown this using about 2/3 less memory.
You can use regular expression on mutable string:
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:
#"[^\\d]"
options:0
error:nil];
[regex replaceMatchesInString:str
options:0
range:NSMakeRange(0, str.length)
withTemplate:#""];
Built the top solution as a category to help with broader problems:
Interface:
#interface NSString (easyReplace)
- (NSString *)stringByReplacingCharactersNotInSet:(NSCharacterSet *)set
with:(NSString *)string;
#end
Implemenation:
#implementation NSString (easyReplace)
- (NSString *)stringByReplacingCharactersNotInSet:(NSCharacterSet *)set
with:(NSString *)string
{
NSMutableString *strippedString = [NSMutableString
stringWithCapacity:self.length];
NSScanner *scanner = [NSScanner scannerWithString:self];
while ([scanner isAtEnd] == NO) {
NSString *buffer;
if ([scanner scanCharactersFromSet:set intoString:&buffer]) {
[strippedString appendString:buffer];
} else {
[scanner setScanLocation:([scanner scanLocation] + 1)];
[strippedString appendString:string];
}
}
return [NSString stringWithString:strippedString];
}
#end
Usage:
NSString *strippedString =
[originalString stringByReplacingCharactersNotInSet:
[NSCharacterSet setWithCharactersInString:#"01234567890"
with:#""];
Swift 3
let notNumberCharacters = NSCharacterSet.decimalDigits.inverted
let intString = yourString.trimmingCharacters(in: notNumberCharacters)
swift 4.1
var str = "75003 Paris, France"
var stringWithoutDigit = (str.components(separatedBy:CharacterSet.decimalDigits)).joined(separator: "")
print(stringWithoutDigit)
Um. The first answer seems totally wrong to me. NSScanner is really meant for parsing. Unlike regex, it has you parsing the string one tiny chunk at a time. You initialize it with a string, and it maintains an index of how far along the string it's gotten; That index is always its reference point, and any commands you give it are relative to that point. You tell it, "ok, give me the next chunk of characters in this set" or "give me the integer you find in the string", and those start at the current index, and move forward until they find something that doesn't match. If the very first character already doesn't match, then the method returns NO, and the index doesn't increment.
The code in the first example is scanning "(123)456-7890" for decimal characters, which already fails from the very first character, so the call to scanCharactersFromSet:intoString: leaves the passed-in strippedString alone, and returns NO; The code totally ignores checking the return value, leaving the strippedString unassigned. Even if the first character were a digit, that code would fail, since it would only return the digits it finds up until the first dash or paren or whatever.
If you really wanted to use NSScanner, you could put something like that in a loop, and keep checking for a NO return value, and if you get that you can increment the scanLocation and scan again; and you also have to check isAtEnd, and yada yada yada. In short, wrong tool for the job. Michael's solution is better.
For those searching for phone extraction, you can extract the phone numbers from a text using NSDataDetector, for example:
NSString *userBody = #"This is a text with 30612312232 my phone";
if (userBody != nil) {
NSError *error = NULL;
NSDataDetector *detector = [NSDataDetector dataDetectorWithTypes:NSTextCheckingTypePhoneNumber error:&error];
NSArray *matches = [detector matchesInString:userBody options:0 range:NSMakeRange(0, [userBody length])];
if (matches != nil) {
for (NSTextCheckingResult *match in matches) {
if ([match resultType] == NSTextCheckingTypePhoneNumber) {
DbgLog(#"Found phone number %#", [match phoneNumber]);
}
}
}
}
`
I created a category on NSString to simplify this common operation.
NSString+AllowCharactersInSet.h
#interface NSString (AllowCharactersInSet)
- (NSString *)stringByAllowingOnlyCharactersInSet:(NSCharacterSet *)characterSet;
#end
NSString+AllowCharactersInSet.m
#implementation NSString (AllowCharactersInSet)
- (NSString *)stringByAllowingOnlyCharactersInSet:(NSCharacterSet *)characterSet {
NSMutableString *strippedString = [NSMutableString
stringWithCapacity:self.length];
NSScanner *scanner = [NSScanner scannerWithString:self];
while (!scanner.isAtEnd) {
NSString *buffer = nil;
if ([scanner scanCharactersFromSet:characterSet intoString:&buffer]) {
[strippedString appendString:buffer];
} else {
scanner.scanLocation = scanner.scanLocation + 1;
}
}
return strippedString;
}
#end
I think currently best way is:
phoneNumber.replacingOccurrences(of: "\\D",
with: "",
options: String.CompareOptions.regularExpression)
If you're just looking to grab the numbers from the string, you could certainly use regular expressions to parse them out. For doing regex in Objective-C, check out RegexKit. Edit: As #Nathan points out, using NSScanner is a much simpler way to parse all numbers from a string. I totally wasn't aware of that option, so props to him for suggesting it. (I don't even like using regex myself, so I prefer approaches that don't require them.)
If you want to format phone numbers for display, it's worth taking a look at NSNumberFormatter. I suggest you read through this related SO question for tips on doing so. Remember that phone numbers are formatted differently depending on location and/or locale.
Swift 5
let newString = origString.components(separatedBy: CharacterSet.decimalDigits.inverted).joined(separator: "")
Based on Jon Vogel's answer here it is as a Swift String extension along with some basic tests.
import Foundation
extension String {
func stringByRemovingNonNumericCharacters() -> String {
return self.componentsSeparatedByCharactersInSet(NSCharacterSet.decimalDigitCharacterSet().invertedSet).joinWithSeparator("")
}
}
And some tests proving at least basic functionality:
import XCTest
class StringExtensionTests: XCTestCase {
func testStringByRemovingNonNumericCharacters() {
let baseString = "123"
var testString = baseString
var newString = testString.stringByRemovingNonNumericCharacters()
XCTAssertTrue(newString == testString)
testString = "a123b"
newString = testString.stringByRemovingNonNumericCharacters()
XCTAssertTrue(newString == baseString)
testString = "a=1-2_3#b"
newString = testString.stringByRemovingNonNumericCharacters()
XCTAssertTrue(newString == baseString)
testString = "(999) 999-9999"
newString = testString.stringByRemovingNonNumericCharacters()
XCTAssertTrue(newString.characters.count == 10)
XCTAssertTrue(newString == "9999999999")
testString = "abc"
newString = testString.stringByRemovingNonNumericCharacters()
XCTAssertTrue(newString == "")
}
}
This answers the OP's question but it could be easily modified to leave in phone number related characters like ",;*#+"
NSString *originalPhoneNumber = #"(123) 123-456 abc";
NSCharacterSet *numbers = [[NSCharacterSet characterSetWithCharactersInString:#"0123456789"] invertedSet];
NSString *trimmedPhoneNumber = [originalPhoneNumber stringByTrimmingCharactersInSet:numbers];
];
Keep it simple!