Objective-C: Find numbers in string
Here's an NSScanner based solution:
// InputNSString *originalString = @"This is my string. #1234";// IntermediateNSString *numberString;NSScanner *scanner = [NSScanner scannerWithString:originalString];NSCharacterSet *numbers = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];// Throw away characters before the first number.[scanner scanUpToCharactersFromSet:numbers intoString:NULL];// Collect numbers.[scanner scanCharactersFromSet:numbers intoString:&numberString];// Result.int number = [numberString integerValue];
(Some of the many) assumptions made here:
- Number digits are 0-9, no sign, no decimal point, no thousand separators, etc. You could add sign characters to the NSCharacterSet if needed.
- There are no digits elsewhere in the string, or if there are they are after the number you want to extract.
- The number won't overflow
int
.
Alternatively you could scan direct to the int
:
[scanner scanUpToCharactersFromSet:numbers intoString:NULL];int number;[scanner scanInt:&number];
If the #
marks the start of the number in the string, you could find it by means of:
[scanner scanUpToString:@"#" intoString:NULL];[scanner setScanLocation:[scanner scanLocation] + 1];// Now scan for int as before.
Self contained solution:
+ (NSString *)extractNumberFromText:(NSString *)text{ NSCharacterSet *nonDigitCharacterSet = [[NSCharacterSet decimalDigitCharacterSet] invertedSet]; return [[text componentsSeparatedByCharactersInSet:nonDigitCharacterSet] componentsJoinedByString:@""];}
Handles the following cases:
- @"1234" → @"1234"
- @"001234" → @"001234"
- @"leading text get removed 001234" → @"001234"
- @"001234 trailing text gets removed" → @"001234"
- @"a0b0c1d2e3f4" → @"001234"
Hope this helps!
You could use the NSRegularExpression class, available since iOS SDK 4.
Bellow a simple code to extract integer numbers ("\d+" regex pattern) :
- (NSArray*) getIntNumbersFromString: (NSString*) string { NSMutableArray* numberArray = [NSMutableArray new]; NSString* regexPattern = @"\\d+"; NSRegularExpression* regex = [[NSRegularExpression alloc] initWithPattern:regexPattern options:0 error:nil]; NSArray* matches = [regex matchesInString:string options:0 range:NSMakeRange(0, string.length)]; for( NSTextCheckingResult* match in matches) { NSString* strNumber = [string substringWithRange:match.range]; [numberArray addObject:[NSNumber numberWithInt:strNumber.intValue]]; } return numberArray; }