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I have a picture slideshow app which allows the user to rate 3 images. The ratings get stored in a NSMutableArray called rated like this:

    2014-01-06 07:10:23.040 SlideShowSurvey[50425:70b] (
    1, <-- Rating for Picture 1
    2, <-- Rating for Picture 2
    3  <-- Rating for Picture 3
)

This is then saved to a .csv file using the following code:

-(void)saveRatings
{
    NSString *picRatings = [NSString stringWithFormat:@"%@, \n",self.rated];
    // Find documents directory
    NSString *docPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *survey = [docPath stringByAppendingPathComponent:@"pictureRatings.csv"];
    // Create new file if none exists
    if (![[NSFileManager defaultManager] fileExistsAtPath:survey])
    {
        [[NSFileManager defaultManager] createFileAtPath:survey contents:nil attributes:nil];
    }
    NSFileHandle *fileHandle = [NSFileHandle fileHandleForUpdatingAtPath:survey];
    [fileHandle seekToEndOfFile];
    [fileHandle writeData:[picRatings dataUsingEncoding:NSUTF8StringEncoding]];
    [fileHandle closeFile];
}

I can then display the results of the .csv file to a UITextView, though it displays it exactly how the array is structured. For example, multiple results display as:

(
    1,
    2,
    3 
),
(
    1,
    2,
    3 
),
(
    1,
    2,
    3 
)

Is there a way I am able to format the array so that it is saved as 1,2,3? And would I be able to add a column header like Picture 1, Picture 2, Picture 3? For example, I would like to display results on the UITextView something like:

Picture 1, Picture 2, Picture 3
1,2,3
1,2,3
1,2,3

I've tried searching but can't seem to find this answer. Any help is appreciated! Thanks.

Edit: I have solved this thanks to jrturton's solution, using the following code:

        // Set column titles for .csv
    NSArray *columnTitleArray = @[@"Picture 1", @"Picture 2", @"Picture 3"];

    NSString *columnTitle = [columnTitleArray componentsJoinedByString:@","];
    NSString *columnTitleToWrite = [columnTitle stringByAppendingString:@"\n"];

    // Separate ratings into cells
    NSString *picRatings = [rated componentsJoinedByString:@","];
    NSString *picRatingsToWrite = [picRatings stringByAppendingString:@"\n"];

    // Find documents directory
..

Then adding this to the method to make sure column headers are only set when a new file is created: 

    // Create new file if none exists
    if (![[NSFileManager defaultManager] fileExistsAtPath:survey])
    {
        [[NSFileManager defaultManager] createFileAtPath:survey contents:nil attributes:nil];

        // Set title for new file
        NSFileHandle *fileHandle = [NSFileHandle fileHandleForUpdatingAtPath:survey];
        [fileHandle writeData:[columnTitleToWrite dataUsingEncoding:NSUTF8StringEncoding]];
    }
..
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2
  • why dont you use custom UITableCellView for display Commented Jan 6, 2014 at 7:48
  • I tried to do that but I only know how to load results from the NSMutableArray itself, not from the .csv file. I'm quite new to Objective-C. Do you know of any code examples showing how to load a .csv into a UITableView? Commented Jan 6, 2014 at 7:53

3 Answers 3

Reset to default
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Here is a much easier way:

NSMutableString *csv = [NSMutableString string];

NSString *label = ...;

[csv appendFormat:@"%@,\n", label];

NSNumber *keyNum = ...;

[csv appendFormat:@"%d,%d\n", [keyNum intValue], [countNum intValue]];

NSString *filename = @"counts.csv";

NSError *error; 

[csv writeToFile:filename atomically:YES encoding:NSUTF8StringEncoding error:&error];
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1 Comment

Please see my updated post, I edited with an attempted solution using some of your code but I can't get it to work. I am unsure what other parts of your code are such as *keyNum and countNum. Can you help me?
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NSMutableString *csv = [NSMutableString string];

NSString *label = @"\n";

[csv appendFormat:@",", label];

NSString *picRatings = [rated componentsJoinedByString:csv];

I'm not sure what you expect appendFormat to be doing in the above code, this will probably be raising a warning since label is not used. You don't need a mutable string in this case either.

To get the contents of an array separated by commas, do this:

NSString *picRatings = [rated componentsJoinedByString:@","];

You also need to add a new line to the end of this string, so you'd want:

NSString *picRatingsToWrite = [picRatings stringByAppendingString:@"\n"];

Write this string to your file and you should be fine.

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3 Comments

Perfect! Your solution is exactly what I need, thanks! The very last thing I'd like is to have column headers, like Picture 1, Picture 2, Picture 3 (as shown in my original post). Do you know how I could achieve this? Thanks a lot for your help.
To do that, just write that string to the file (with a trailing \n) if there isn't anything in there already, or add it to the start of your first-ever rating string.
Brilliant, I was able to set column headers when creating the file, I have updated my post to show this. Thanks for all your help!
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use this parser and get the data into array and look how you can use data into UITabelViewCell https://github.com/davedelong/CHCSVParser

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1 Comment

I've thought about a CSV parser but this app is very simple and stores only a small amount of data in the .csv file, so I decided against trying to implement a parser. Thanks for the reply though.

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