Search for images in resources

Question

I have a project, which contains images in its resources. For example: image1yellow.png, image2red.png, image3green.png... The number of these images could be different, but my app has to know the number and their names. So I want to collect these images from the resources by searching for them... The 'image' part of the title is constant and right after that there is a number. The final part of the title is always a color name (so..variable strings) >>> image+3+green=image3green. I think somehow I can search with these criterias...

Answer 1

EDIT

Actually, NSBundle has an even more convienient method :

URLsForResourcesWithExtension:subdirectory:inBundleWithURL:

With this you can get an array of all your png ressources and then use it to determine which image you want.

To get the ressources starting with image you can then use :

    NSArray * array = [NSBundle URLsForResourcesWithExtension:@"png" subdirectory:nil inBundleWithURL:[[NSBundle mainBundle] bundleURL]];
    [array indexesOfObjectsPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
        return [obj isKindOfClass:NSURL.class] && [[((NSURL *) obj) resourceSpecifier] hasPrefix:@"image"];
    }];

Of course, this is NOT the best way to retrieve it, I'm almost sure you have some simple logic to get the end of the image name, you can probably have a better algorithm (maybe you could just sort the array and use an enumerator). Also you might want to keep the final result (e.g. all ressources starting with image) in a static field to retrieve them faster, instead of redoing all the work each time.

Basically, you have to do the rest of the implementation according to what you really want to have (or give example of your logic to get the final image).

Original response

I'm not sure I understand what you want but I think it's something like that :

    NSArray * ressources = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:[[NSBundle mainBundle] resourcePath] error:&error];

You could also consider

contentsOfDirectoryAtURL:includingPropertiesForKeys:options:error:

Answer 2

Since you know the structure of the file name, create a new NSString with a particular format given a set of variables:

NSUInteger arbitraryNumber = 7;
NSString *color = @"yellow";
NSString *extension = @"png";
NSString *imageName = [NSString stringWithFormat:@"image%d%@.%@", arbitraryNumber, color, extension];

Or assign these images to an array in a loop...

EDIT: After clear oversight with the question at hand...

The following is a recursive solution using regular expressions to get the desired "phrase" in a filename. I wrote this just for you and tested it. Of course, this stuff is kind of tricky so if you hand it a file name like "images23green.png" it may fail. If you're concerned about this, you should learn more about regular expressions!

To have this execute, just call [self loadImages].

- (void)loadImages
{
    NSDictionary *filenameElements = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:@"^(image)\\d+\\w+\\.\\w{3}$", @"^(image)", @"^\\d+", @"^\\w+", @"^\\w{3}", nil] forKeys:[NSArray arrayWithObjects:@"filename", @"image", @"number", @"color", @"fileExtension", nil]];
    NSString *string = @"image23green.png";      // Example file name
    NSError *error = NULL;
    error = [self searchForSubstring:@"image" inString:string withRegexFormatDictionary:filenameElements beginAtIndex:0];
}

- (NSError *)searchForSubstring:(NSString *)key inString:(NSString *)givenString withRegexFormatDictionary:(NSDictionary *)filenameElements beginAtIndex:(NSInteger)index
{
    NSError *error = NULL;
    NSString *substring = [givenString substringFromIndex:index];

    NSString *regexPattern = [filenameElements objectForKey:key];
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:regexPattern options:NSRegularExpressionCaseInsensitive error:&error];
    NSArray *matches = [regex matchesInString:substring options:0 range:NSMakeRange(0, [substring length])];
    if ([matches count] > 0)
    {
        NSRange matched = [[matches objectAtIndex:0] rangeAtIndex:0];
        NSLog(@"matched: %@", [substring substringWithRange:matched]);

        index = 0;
        NSString *nextKey;
        if      ([key isEqualToString:@"image"])         { nextKey = @"number"; index = matched.length; }
        else if ([key isEqualToString:@"number"])        { nextKey = @"color"; index = matched.length; }
        else if ([key isEqualToString:@"color"])         { nextKey = @"fileExtension"; index = matched.length + 1; }
        else if ([key isEqualToString:@"fileExtension"]) { nextKey = nil; }
        if (nextKey)
            error = [self searchForSubstring:nextKey inString:substring withRegexFormatDictionary:filenameElements beginAtIndex:index];
    }
    return error;
}

This solution accepts a filename with a numeric value of any length, any color name length that will only accept alphabetical characters (i.e., no hyphens allowed) and a 3 character long file extension. This may be changed by replacing {3} to {3-4} if you want a range of 3 to 4 character length, and so on...