Get the extension of a file contained in an NSString

Question

I have an NSMutable dictionary that contains file IDs and their filename+extension in the simple form of fileone.doc or filetwo.pdf. I need to determine what type of file it is to correctly display a related icon in my UITableView. Here is what I have done so far.

NSString *docInfo = [NSString stringWithFormat:@"%d", indexPath.row]; //Determine what cell we are formatting
NSString *fileType = [contentFiles objectForKey:docInfo]; //Store the file name in a string

I wrote two regex to determine what type of file I'm looking at, but they never return a positive result. I haven't used regex in iOS programming before, so I'm not entirely sure if I'm doing it right, but I basically copied the code from the Class Description page.

    NSError *error = NULL;
NSRegularExpression *regexPDF = [NSRegularExpression regularExpressionWithPattern:@"/^.*\\.pdf$/" options:NSRegularExpressionCaseInsensitive error:&error];
NSRegularExpression *regexDOC = [NSRegularExpression regularExpressionWithPattern:@"/^.*\\.(doc|docx)$/" options:NSRegularExpressionCaseInsensitive error:&error];
    NSUInteger numMatch = [regexPDF numberOfMatchesInString:fileType options:0 range:NSMakeRange(0, [fileType length])];
    NSLog(@"How many matches were found? %@", numMatch);

My questions would be, is there an easier way to do this? If not, are my regex incorrect? And finally if I have to use this, is it costly in run time? I don't know what the average amount of files a user will have will be.

Thank you.

Answer 1

You're looking for [fileType pathExtension]

NSString Documentation: pathExtension