Extracts the scale factor (e.g. 1x, 2x, 3x) of an image file name as a float.

Image Scale Factor from File Name

- (CGFloat) imageScaleFactorFromFilename:(NSString*) imageFileName
{
    NSString* filename = [imageFileName stringByDeletingPathExtension];
    
    NSArray* components = [filename componentsSeparatedByString:@"@"];
    
    if ([components count] > 1) {
        // Hi res image
        
        NSString* scaleSubstring = [components objectAtIndex:1];    // e.g. @"2x"
        
        scaleSubstring = [scaleSubstring stringByReplacingOccurrencesOfString:@"x" withString:@""];
        
        CGFloat scaleFactor = [scaleSubstring floatValue];
        
        return scaleFactor;
    }
    
    return 1.0f;
}