How to format string encoded with NSASCIIStringEncoding - objective-c

Question

In my Objective-C project, I'm fetching a key from cloudKit and wanted to format it before like this and wondering what's wrong with the formatting,
[cloudKitDB performQuery:query inZoneWithID:nil completionHandler:^(NSArray<CKRecord *> * _Nullable results, NSError * _Nullable error) {
NSString *key = [[NSString alloc] initWithData:[results.firstObject objectForKey:#"keyvalue"] encoding:NSASCIIStringEncoding];
NSLog(#"First Key Output: %#",key);
NSLog(#"Second Key Output: %#",key);
NSString *formattedKey = [NSString stringWithFormat:#"%#%#",[key stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]], #"1234"];
NSLog(#"Formatted Key: %#",formattedKey);
And here my logged
2020-08-15 21:08:14.704650+0700 myapp[2208:79554] First Key Output: ADEvXp2F2BFJ2E4Lm2dSnYvHENhkFrK8
2020-08-15 21:08:14.704828+0700 myapp[2208:79554] Second Key Output: ADEvXp2F2BFJ2E4Lm2dSnYvHENhkFrK8
2020-08-15 21:08:14.705456+0700 myapp[2208:79554] Formatted Key: ADEvXp2F2BFJ2E4Lm2dSnYvHENhkFrK8
Although, I have tried to trim whitespace but still no luck!
Thanks

Answer 1

This is a strange problem, but I can reproduce it with the code below.
Based on this I still suspect that there are some funnies behind the string and have given ways to fix it in the code.
// Note C strlen will stop at the first 0
char * s = "3Lm9dGmeTf3Lm9dGmeTf3Lm9dGmeTfdd\0\0\0";
NSData * data = [NSData dataWithBytes:s length:strlen( s ) + 2];
NSString * key = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
NSString * keyFormatted = [NSString stringWithFormat:#"%#%#", key, #"1234"];
NSLog ( #"Key : %#", key );
NSLog ( #"Formatted key: %#", keyFormatted );
// Use strlen to get rid of funnies
NSData * dataFixed = [data subdataWithRange:NSMakeRange( 0, strlen( s ) )];
NSString * keyFixed = [[NSString alloc] initWithData:dataFixed encoding:NSASCIIStringEncoding];
NSString * keyForm2 = [NSString stringWithFormat:#"%#%#", keyFixed, #"1234"];
NSLog ( #"Fixed key : %#", keyFixed );
NSLog ( #"Formatted key: %#", keyForm2 );
// Use C isprint to trim ... crude but works
while ( key.length && ! isprint ( [key characterAtIndex:key.length - 1] ) )
{
key = [key substringToIndex:key.length - 1];
}
keyFormatted = [NSString stringWithFormat:#"%#%#", key, #"1234"];
NSLog ( #"Key : %#", key );
NSLog ( #"Formatted key: %#", keyFormatted );