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Editorial Team
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Asked: 2026-06-04T19:04:17+00:00

NSString*test=[NSString stringWithString:inputString]; NSScanner*scan; BOOL pass= [scan scanUpToCharactersFromSet:[[NSCharacterSet alphanumericCharacterSet] invertedSet] intoString:&test]; The last line crashes

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NSString*test=[NSString stringWithString:inputString]; 
NSScanner*scan;
BOOL pass= [scan scanUpToCharactersFromSet:[[NSCharacterSet alphanumericCharacterSet] invertedSet] intoString:&test];

The last line crashes the app with bad access. Does it have something to do with the address symbol, &? I’m not clear on why it needs this type of syntax anyway.

I am trying to simply check with my BOOL if the inputString contains any non-alphanumeric characters. If it does, pass becomes YES.

UPDATE: I see I do not understand scanner entirely. I understand this output:

NSString*test=@"Hello"; // this should cause my BOOL to be NO since no characters are scanned
NSScanner*scanix=[NSScanner scannerWithString:test];
BOOL pass= [scanix scanUpToCharactersFromSet:[[NSCharacterSet alphanumericCharacterSet] invertedSet] intoString:nil];
NSLog(@"pass is %i for %@",pass, test);

Result in log: pass is 1 for Hello

What I want is to know if in fact the test string contains non-alphanumeric characters. How would I factor such a test into this?

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1 Answer

  1. Editorial Team

    What I want is to know if in fact the test string contains
    non-alphanumeric characters. How would I factor such a test into this?

    You don’t need to use NSScanner if this is your only goal. You can simply use NSString’s -rangeOfCharacterFromSet: method:

    NSCharacterSet *nonAlphanumeric = [[NSCharacterSet alphanumericCharacterSet] invertedSet];
pass = ([test rangeOfCharacterFromSet:nonAlphanumeric].location != NSNotFound);
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