Scan for numbers in Objective - C

Question

I wonder how could I able to find all the numbers as follows.

Input

NSString* input = @ "1m3s"

The desired output

@[@"1" @"3"]

I have tried the following approach

NSArray *arr = [input componentsSeparatedByCharactersInSet:
                        [NSCharacterSet characterSetWithCharactersInString:@"ms"]];

it returned me

@[@"1",@"3",@"@"]

Is there a better approach to solve this problem, any suggestion?

Even though this question has been marked as a duplication, I have tested the following answer but did not work.

Update

That could be any string value.

if input is @"11m32s" or @11m32 and then desired output would be @[@"11", @"32"];

if input is @"11x32" or @11x32y and then desired output would be @[@"11", @"32"];

Look at the NSString method `componentsSeparatedByCharactersInSet` and pass the output from that to what you have already been doing. — Gary Makin, Jul 11 '17 at 03:42
@Nirav, I have tested both approach in the given answer, none of them works. Feel free to test with given input. Please remove duplication. — casillas, Jul 11 '17 at 04:06
hi hotspring, please check https://stackoverflow.com/a/45025228/4061501 — Lal Krishna, Jul 11 '17 at 04:13
@hotspring I have removed the duplicate request and added solution — Nirav D, Jul 11 '17 at 04:26
Possible duplicate of [Objective-C: Find numbers in string](https://stackoverflow.com/questions/4663438/objective-c-find-numbers-in-string) — dandan78, Jul 11 '17 at 08:38

Stefanf · Answer 1 · 2017-07-11T08:46:18.353

3

Using a NSScanner would allow you to scan floats as well. In addition your array is populated directly with NSNumber instead of NSString.

NSString * input = @ "12m32s";
NSScanner * aScanner = [NSScanner scannerWithString:input];
NSInteger aInt;
NSMutableArray * result = [NSMutableArray array];
while (!aScanner.isAtEnd)
{
    if ([aScanner scanInteger:&aInt])
    {
        [result addObject:@(aInt)];
    }
    if (!aScanner.isAtEnd)
    {
        aScanner.scanLocation += 1;
    }
}
NSLog(@"%@",result);

edited Jul 11 '17 at 08:46

answered Jul 11 '17 at 08:35

Stefanf

1,663
13
15

This is a much better solution. – Martin Hering Jul 11 '17 at 08:57

score 1 · Accepted Answer · answered Jul 11 '17 at 04:09

1

Try:

NSString* input = @ "1m3s";
NSCharacterSet *nonDigitCharacterSet = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
NSArray *outArray = [input componentsSeparatedByCharactersInSet:nonDigitCharacterSet];
outArray = [outArray filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"length > 0"]];

answered Jul 11 '17 at 04:09

Lal Krishna

15,485
6
64
84

1

If the input `[11m32s]` then it fails. The desired output `[11, 32]`. I have upvoted your effort. – casillas Jul 11 '17 at 04:18
Thank you! But when I input `[11m32s]`, I got result Array: ( 11, 32 ) with the same code – Lal Krishna Jul 11 '17 at 04:24
I also tested for `11m32s` & `11m32` and got ( 11, 32 ) when I log the result array – Lal Krishna Jul 11 '17 at 04:27

vadian · Answer 3 · 2017-07-11T04:48:14.283

To extract numbers you can use Regular Expression.

NSString* input = @ "1m3s";
NSString *pattern = @"\\d+"; // searches for one or more digits
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:pattern options:0 error:nil];
NSArray *matches = [regex matchesInString:input options:0 range:NSMakeRange(0, input.length)];
NSMutableArray *result = [[NSMutableArray alloc] init];
for (NSTextCheckingResult *match in matches) {
    [result addObject: [input substringWithRange:match.range]];
}
NSLog(@"%@", result);

Or if you want to be more specific and extract the numbers in an expression ##m##s use

NSString* input = @ "1m3s";
NSString *pattern = @"(\\d+)m(\\d+)s";
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:pattern options:0 error:nil];
NSTextCheckingResult *match = [regex firstMatchInString:input options:0 range:NSMakeRange(0, input.length)];
if (match) {
    NSArray *result = @[[input substringWithRange:[match rangeAtIndex:1]], [input substringWithRange:[match rangeAtIndex:2]]];
    NSLog(@"%@", result);
}

what if input is `@"11x32"` or `@11x32y` as I mentioned in the question it can be any character? — casillas, Jul 11 '17 at 04:48
The first version covers both. It considers any occurrence of one or more digits in a string. — vadian, Jul 11 '17 at 04:49
Using RegEx is totally overkill and slow. Just use NSScanner. — Martin Hering, Jul 11 '17 at 08:58

score 0 · Answer 4 · answered Jul 11 '17 at 03:53

I think's it's helpful for you below the code work for me.

NSString *originalString = @"1m3s";
    NSMutableArray *arr = [[NSMutableArray alloc] init];
    for (int i=0; i<[originalString length]; i++) {
        if (isdigit([originalString characterAtIndex:i])) {
            NSMutableString *strippedString = [NSMutableString stringWithCapacity:10];
            [strippedString appendFormat:@"%c",[originalString characterAtIndex:i]];
            [arr addObject:strippedString];
        }
    }
    NSLog(@"%@",arr.description);

The use of `%c` will only work for ASCII (8-bit) characters. But `characterAtIndex` returns 16-bit characters. At least use `%C`. — rmaddy, Jul 11 '17 at 03:54

Vinit Ingale · Answer 5 · 2017-07-11T04:00:53.090

0

Use below code :

 NSCharacterSet *nonDigitCharacterSet = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
 NSArray *outArray = [[input componentsSeparatedByCharactersInSet:nonDigitCharacterSet] componentsJoinedByString:@""];

edited Jul 11 '17 at 04:00

answered Jul 11 '17 at 03:54

Vinit Ingale

381
1
4
17

2

the output is not `NSArray`? – casillas Jul 11 '17 at 03:56

nayem · Answer 6 · 2017-07-11T04:06:36.743

0

Use this handy approach:

+ (NSArray *)extractNumberFromText:(NSString *)text
{
    NSCharacterSet *nonDigitCharacterSet = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
    NSMutableArray *numberArray = [[text componentsSeparatedByCharactersInSet:nonDigitCharacterSet]mutableCopy];
    [numberArray removeObject:@""];
    return numberArray;
}

edited Jul 11 '17 at 04:06

answered Jul 11 '17 at 03:58

nayem

7,285
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That also returns me `@[@"1",@"3",@"@"]` – casillas Jul 11 '17 at 04:02
Nope. If you have non digit character at the last then you will get an `empty` string. Removing the empty one from the array will get you the numbers only. – nayem Jul 11 '17 at 04:09

score 0 · Answer 7 · answered Jul 11 '17 at 04:12

Here is code to get your desire output:

  NSString* input = @"1m3s";

        NSString *newString = [[input componentsSeparatedByCharactersInSet:
                                [[NSCharacterSet decimalDigitCharacterSet] invertedSet]]
                               componentsJoinedByString:@""];


        NSMutableArray *array = [NSMutableArray array];
        for (int i = 0; i < [newString length]; i++) {
            NSString *ch = [newString substringWithRange:NSMakeRange(i, 1)];
            [array addObject:ch];
        }


        NSLog(@"%@",array.description);

score 0 · Answer 8 · answered Jul 11 '17 at 04:43

You can also use this code bellow.

NSString * String = @"24fsd35rf";
NSArray* Array = [String componentsSeparatedByCharactersInSet:
                              [[NSCharacterSet decimalDigitCharacterSet] invertedSet]];
NSLog(@"%@",[Array filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"self <> ''"]]);

Scan for numbers in Objective - C

8 Answers8