Question

Im having problems filtering an array using a predicate. My code is this one:

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSError *error;
NSFileManager *fm = [NSFileManager defaultManager];
NSString *filename=[NSString stringWithFormat:@"%@/%lld-%@.jpg",[paths objectAtIndex:0],[TRIP surrogateKey], ms];

NSArray *dirContents = [fm contentsOfDirectoryAtPath:[paths objectAtIndex:0] error:&error];
NSPredicate *fltr = [NSPredicate predicateWithFormat:@"SELF beginsWith %lld-%@",[TRIP surrogateKey], ms];
NSArray *registros=[dirContents filteredArrayUsingPredicate:fltr];

in the debug session i found that i have a problem performing the last line of the code (NSArray *registros=[dirContents filteredArrayUsingPredicate:fltr]) and it gives me the following error:

-[__NSCFString objCType]: unrecognized selector sent to instance 0x7e67200 2013-02-01 16:37:59.132 GastosApp[4462:11303] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFString objCType]: unrecognized selector sent to instance 0x7e67200'

In the debug section i saw that the memory 0x7e67200 is occupied by the ms variable which is declared:

NSMutableString *ms = [[NSMutableString new] autorelease];

Does anyone see any mistake?

Thanks and regards

Answer 1

May be error because NSPredicate make automatic quotation for format variables like %@.

For example, this:

[NSPredicate
    predicateWithFormat:@"SELF like[c] %@*%@", prefix, suffix];

Will be as: SELF LIKE[c] "prefix" * "suffix"

Right way:

[NSPredicate
    predicateWithFormat:@"SELF like[c] %@",
    [[prefix stringByAppendingString:@"*"] stringByAppendingString:suffix]];

Which give us a correct result: SELF LIKE[c] "prefix*suffix"