[WP/1049] NSCharacterSet vs. NSRegularExpressionSearch vs. NSScanner

0.m

// NSCharacterSet
NSCharacterSet *allowedCharacterSet = [NSCharacterSet characterSetWithCharactersInString:@"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_"];
NSString *deviceNameString = [[[[UIDevice currentDevice] name] componentsSeparatedByCharactersInSet:[allowedCharacterSet invertedSet]] componentsJoinedByString:@""];

1.m

// NSRegularExpressionSearch
NSString *deviceNameString = [[UIDevice currentDevice] name];
NSString *regularExpressionString = @"([a-zA-Z0-9_-])+";

NSMutableString *resultString = [NSMutableString string];
NSInteger location = 0;
while (location < [deviceNameString length]) {
    NSString *string = [deviceNameString substringFromIndex:location];
    NSRange range = [string rangeOfString:regularExpressionString options:NSRegularExpressionSearch];
    if (range.location != NSNotFound) {
        [resultString appendString:[string substringWithRange:range]];
        location += range.location + range.length;
    } else {
        break;
    }
}

2.m

// NSScanner
NSString *deviceNameString = [[UIDevice currentDevice] name];

NSCharacterSet *charset = [NSCharacterSet characterSetWithCharactersInString:@"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_"];
charset = [charset invertedSet];

NSScanner *scanner = [NSScanner scannerWithString:deviceNameString];
NSString *tempString = nil;
NSString *resultString = [NSString string];
while(![scanner isAtEnd]) {
    [scanner setCharactersToBeSkipped:charset];
    [scanner charactersToBeSkipped];
    
    [scanner scanUpToCharactersFromSet:charset intoString:&tempString];
    if (tempString != nil) {
        resultString = [resultString stringByAppendingString:tempString];
    }
}