I am new to learning Objective-C (my first programming language!) and trying to write a little program that will add 1 to a number contained within a string. E.g. AA1BB becomes AA2BB.
.
So far I have tried to extract the number and add 1. Then extract the letters and add everything back together in a new string. I have had some success but can't manage to get back to the original arrangement of the initial string.
The code I have so far gives a result of 2BB and disregards the characters before the number which is not what I am after (the result I am trying for with this example would be AA2BB). I can't figure out why!
NSString* aString = #"AA1BB";
NSCharacterSet *numberCharset = [NSCharacterSet characterSetWithCharactersInString:#"0123456789-"]; //Creating a set of Characters object//
NSScanner *theScanner = [NSScanner scannerWithString:aString];
int someNumbers = 0;
while (![theScanner isAtEnd]) {
// Remove Letters
[theScanner scanUpToCharactersFromSet:numberCharset
intoString:NULL];
if ([theScanner scanInt:&someNumbers]) {}
}
NSCharacterSet *letterCharset = [NSCharacterSet characterSetWithCharactersInString:#"ABCDEFGHIJKLMNOPQRSTUVWXYZ"];
NSScanner *letterScanner = [NSScanner scannerWithString:aString];
NSString* someLetters;
while (![letterScanner isAtEnd]) {
// Remove numbers
[letterScanner scanUpToCharactersFromSet:letterCharset
intoString:NULL];
if ([letterScanner scanCharactersFromSet:letterCharset intoString:&someLetters]) {}
}
++someNumbers; //adds +1 to the Number//
NSString *newString = [[NSString alloc]initWithFormat:#"%i%#", someNumbers, someLetters];
NSLog (#"String is now %#", newString);
This is an alternative solution with Regular Expression.
It finds the range of the integer (\\d+ is one or more digits), extracts it, increments it and replaces the value at the given range.
NSString* aString = #"AA1BB";
NSRange range = [aString rangeOfString:#"\\d+" options:NSRegularExpressionSearch];
if (range.location != NSNotFound) {
NSInteger numericValue = [aString substringWithRange:range].integerValue;
numericValue++;
aString = [aString stringByReplacingCharactersInRange:range withString:[NSString stringWithFormat:#"%ld", numericValue]];
}
NSLog(#"%#", aString);
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;
I have a NSArray containing NSStrings with emoji codes in the following format:
0x1F463
How can I now convert them into a NSString with the correct format?
With this method I am able to generate an "Emoji"-NSString:
NSString *emoji = [NSString stringWithFormat:#"\U0001F463"];
But this is only possible with constant NSStrings. How can I convert the whole NSArray?
Not my best work, but it appears to work:
for (NSString *string in array)
{
#autoreleasepool {
NSScanner *scanner = [NSScanner scannerWithString:string];
unsigned int val = 0;
(void) [scanner scanHexInt:&val];
NSString *newString = [[NSString alloc] initWithBytes:&val length:sizeof(val) encoding:NSUTF32LittleEndianStringEncoding];
NSLog(#"%#", newString);
[newString release]; // don't use if you're using ARC
}
}
Using an array of four of your sample value, I get four pairs of bare feet.
You can do it like this:
NSString *str = #"0001F463";
// Convert the string representation to an integer
NSScanner *hexScan = [NSScanner scannerWithString:str];
unsigned int hexNum;
[hexScan scanHexInt:&hexNum];
// Make a 32-bit character from the int
UTF32Char inputChar = hexNum;
// Make a string from the character
NSString *res = [[NSString alloc] initWithBytes:&inputChar length:4 encoding:NSUTF32LittleEndianStringEncoding];
// Print the result
NSLog(#"%#", res);
I am developing an apps for iPad. I am wondering that how can I find out whether a string is convertable to double or not. For example, both [myString floatValue] and numberFromString method of NSNumberFormatter recognize some string like "123rrrrr" as a valid number and returns its number part which is 123!
Could you help me?
You can use a NSScanner for these purposes. It has methods to filter floats and doubles from strings.
http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSScanner_Class/Reference/Reference.html
The NSNumberFormatter method getObjectValue:forString:range:error will do what you want. This will parse a number in a given range of a string - set this to the whole string - and return the range of the string it used - if this range doesn't extend to the end of the string there is garbage after the number.
Here is a simple wrapper for it:
- (BOOL) getNumberValue:(out NSNumber **)parsedNumber
forString:(NSString *)inputString
error:(out NSError **)error
{
NSNumberFormatter *parser = [NSNumberFormatter new];
// remove whitespace so we can easily test if the whole string was parsed OK
NSString *trimmed = [inputString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
NSUInteger trimmedLength = [trimmed length];
NSRange all = NSMakeRange(0, trimmedLength);
BOOL status = [parser getObjectValue:parsedNumber forString:trimmed range:&all error:error];
if(status && all.length != trimmedLength)
{ // getObjectValue succeeded but garbage after number (if garbage before number getObjectValue will fail)
if (error != NULL)
{ // make appropriate error
*error = [NSError errorWithDomain:NSCocoaErrorDomain
code:NSFormattingError
userInfo:[NSDictionary dictionaryWithObject:[NSString stringWithFormat:#"The value “%#” is invalid.", inputString]
forKey:NSLocalizedDescriptionKey]];
}
status = NO;
}
return status;
}
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!