Question

I have an excel file with some data (with multiple columns and multiple rows). I want to import this data into my core-data based database. I’m struggling to import the data, because the text in the cells contain line breaks.

I’ve tried the following:

1.) Export excel to Tab-delimited text file

2.) Write an import route in iOS that reads the tab-delimited text file using the following code:

NSCharacterSet *tabCharacterSet = [NSCharacterSet characterSetWithCharactersInString:@"\t"];

NSArray *rows = [dataString componentsSeparatedByCharactersInSet:[NSCharacterSet newlineCharacterSet]];
NSArray *columns = [row componentsSeparatedByCharactersInSet:tabCharacterSet];

Problem: I have 1000 rows with 15 columns each. The parsing routine returns more than 1000 rows and less than 15 columns. The line breaks with-in the cell are not being handled properly by the parsing routine.

I get the same results if I use

[NSCharacterSet characterSetWithCharactersInString:@"\r\n"];

or

[NSCharacterSet characterSetWithCharactersInString:@"\r"];

instead of

[NSCharacterSet newlineCharacterSet]

but it completely fails if I use

[NSCharacterSet characterSetWithCharactersInString:@"\n"];

How can I parse the excel-data properly?

Perhaps I can use Regex expressions to get line components? Any idea/pointers?

UPDATE (Sample XLSX and Export File):

Answer 1

The solution that worked for me involves using NSScanner class.

- (NSArray *)parseCSVFileString {
    NSMutableArray *rows = [NSMutableArray array];

    // Get newline character set
    NSMutableCharacterSet *newlineCharacterSet = (id)[NSMutableCharacterSet whitespaceAndNewlineCharacterSet];
    [newlineCharacterSet formIntersectionWithCharacterSet:[[NSCharacterSet whitespaceCharacterSet] invertedSet]];

    // Characters that are important to the parser
    NSMutableCharacterSet *importantCharactersSet = (id)[NSMutableCharacterSet characterSetWithCharactersInString:@",\""];
    [importantCharactersSet formUnionWithCharacterSet:newlineCharacterSet];

    // Create scanner, and scan string
    NSScanner *scanner = [NSScanner scannerWithString:self];
    [scanner setCharactersToBeSkipped:nil];

    while (![scanner isAtEnd]) {

        @autoreleasepool {
            BOOL insideQuotes = NO;
            BOOL finishedRow = NO;
            NSMutableArray *columns = [NSMutableArray arrayWithCapacity:10];
            NSMutableString *currentColumn = [NSMutableString string];
            while ( !finishedRow ) {
                NSString *tempString;

                if ([scanner scanUpToCharactersFromSet:importantCharactersSet intoString:&tempString]) {
                    [currentColumn appendString:tempString];
                }

                if ([scanner isAtEnd]) {

                    if (![currentColumn isEqualToString:@""]) [columns addObject:currentColumn];

                    finishedRow = YES;

                } else if ([scanner scanCharactersFromSet:newlineCharacterSet intoString:&tempString]) {

                    if (insideQuotes) {
                        // Add line break to column text
                        [currentColumn appendString:tempString];

                    } else {
                        // End of row
                        if (![currentColumn isEqualToString:@""]) [columns addObject:currentColumn];

                        finishedRow = YES;
                    }

                } else if ([scanner scanString:@"\"" intoString:NULL]) {

                    if (insideQuotes && [scanner scanString:@"\"" intoString:NULL]) {
                        // Replace double quotes with a single quote in the column string.
                        [currentColumn appendString:@"\""];

                    } else {
                        // Start or end of a quoted string.
                        insideQuotes = !insideQuotes;
                    }

                } else if ([scanner scanString:@"," intoString:NULL]) {

                    if (insideQuotes) {
                        [currentColumn appendString:@","];

                    } else {
                        // This is a column separating comma
                        [columns addObject:currentColumn];
                        currentColumn = [NSMutableString string];
                        [scanner scanCharactersFromSet:[NSCharacterSet whitespaceCharacterSet] intoString:NULL];
                    }
                }
            }

            if ( [columns count] > 0 ) [rows addObject:columns];
        }
    }

    return rows;
}

Reference: http://www.macresearch.org/cocoa-scientists-part-xxvi-parsing-csv-data