NSString - Convert to pure alphabet only (i.e. remove accents+punctuation)

I'm trying to compare names without any punctuation, spaces, accents etc. At the moment I am doing the following:

-(NSString*) prepareString:(NSString*)a {
    //remove any accents and punctuation;
    a=[[[NSString alloc] initWithData:[a dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES] encoding:NSASCIIStringEncoding] autorelease];

    a=[a stringByReplacingOccurrencesOfString:@" " withString:@""];
    a=[a stringByReplacingOccurrencesOfString:@"'" withString:@""];
    a=[a stringByReplacingOccurrencesOfString:@"`" withString:@""];
    a=[a stringByReplacingOccurrencesOfString:@"-" withString:@""];
    a=[a stringByReplacingOccurrencesOfString:@"_" withString:@""];
    a=[a lowercaseString];
    return a;
}

However, I need to do this for hundreds of strings and I need to make this more efficient. Any ideas?

Edit Report

One important precision over the answer of BillyTheKid18756 (that was corrected by Luiz but it was not obvious in the explanation of the code):

DO NOT USE stringWithCString as a second step to remove accents, it can add unwanted characters at the end of your string as the NSData is not NULL-terminated (as stringWithCString expects it). Or use it and add an additional NULL byte to your NSData, like Luiz did in his code.

I think a simpler answer is to replace:

NSString *sanitizedText = [NSString stringWithCString:[sanitizedData bytes] encoding:NSASCIIStringEncoding];

By:

NSString *sanitizedText = [[[NSString alloc] initWithData:sanitizedData encoding:NSASCIIStringEncoding] autorelease];

If I take back the code of BillyTheKid18756, here is the complete correct code:

// The input text
NSString *text = @"BûvérÈ!@$&%^&(*^(_()-*/48";

// Defining what characters to accept
NSMutableCharacterSet *acceptedCharacters = [[NSMutableCharacterSet alloc] init];
[acceptedCharacters formUnionWithCharacterSet:[NSCharacterSet letterCharacterSet]];
[acceptedCharacters formUnionWithCharacterSet:[NSCharacterSet decimalDigitCharacterSet]];
[acceptedCharacters addCharactersInString:@" _-.!"];

// Turn accented letters into normal letters (optional)
NSData *sanitizedData = [text dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
// Corrected back-conversion from NSData to NSString
NSString *sanitizedText = [[[NSString alloc] initWithData:sanitizedData encoding:NSASCIIStringEncoding] autorelease];

// Removing unaccepted characters
NSString* output = [[sanitizedText componentsSeparatedByCharactersInSet:[acceptedCharacters invertedSet]] componentsJoinedByString:@""];

answered 2012-07-26T10:29:16.330

NSString - Convert to pure alphabet only (i.e. remove accents+punctuation)

1 Answer

Your Answer