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.

David Barry · Accepted Answer · 2012-02-12T00:05:29.913

154

You're looking for [fileType pathExtension]

NSString Documentation: pathExtension

edited Feb 12 '12 at 00:05

answered Feb 11 '12 at 23:59

David Barry

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1

Oh, didn't knew that NSString have the `pathExtension` property – remy Feb 12 '12 at 00:02
4

Objective-C just makes things so easy; I need to not think of such hard solutions! Thank you David. – jer-k Feb 13 '12 at 00:40
3

Im glad I didnt try and make this function myself – Will Oct 12 '12 at 14:23

remy · Answer 2 · 2012-02-12T00:04:06.253

7

//NSURL *url = [NSURL URLWithString: fileType];
NSLog(@"extension: %@", [fileType pathExtension]);

Edit you can use pathExtension on NSString

Thanks to David Barry

edited Feb 12 '12 at 00:04

answered Feb 11 '12 at 23:57

remy

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You can call pathExtension directly on the String, no need to create an NSURL first. – David Barry Feb 12 '12 at 00:01
3

Why have you just ripped the answer above and then credited him? – Adam Waite Mar 30 '14 at 12:52

score 4 · Answer 3 · edited Jul 07 '15 at 10:49

4

Try this :

NSString *fileName = @"resume.doc";  
NSString *ext = [fileName pathExtension];

edited Jul 07 '15 at 10:49

byJeevan

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answered Feb 04 '15 at 12:09

Aatish Javiya

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score 3 · Answer 4 · answered Mar 31 '17 at 19:54

3

Try this, it works for me.

NSString *fileName = @"yourFileName.pdf";
NSString *ext = [fileName pathExtension];

Documentation here for NSString pathExtension

answered Mar 31 '17 at 19:54

Ashu

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score 1 · Answer 5 · answered Feb 12 '12 at 00:00

1

Try using [fileType pathExtension] to get the extension of the file.

answered Feb 12 '12 at 00:00

Eric

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score 0 · Answer 6 · answered Jan 10 '17 at 18:12

0

In Swift 3 you could use an extension:

extension String {

public func getExtension() -> String? {

        let ext = (self as NSString).pathExtension

        if ext.isEmpty {
            return nil
        }

        return ext
    }
}

answered Jan 10 '17 at 18:12

Domenico

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Get the extension of a file contained in an NSString

6 Answers6

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