Escaping Strings in Swift

Question

I am going to create a CSV file programmatically and would like to properly escape my strings before writing them.

I assume I'll need to escape commas and probably need to surround each value in single or double quotes (and thus will need to escape those too). Plus any carriage return / new line constants.

I was going to write it all myself but then found this in Objective-C and said why not just convert it, as it looks quite thorough:

-(NSString *)escapeString:(NSString *)s
{
    NSString * escapedString = s;   
    BOOL containsSeperator = !NSEqualRanges([s rangeOfString:@","], NSMakeRange(NSNotFound, 0));
    BOOL containsQuotes = !NSEqualRanges([s rangeOfString:@"\""], NSMakeRange(NSNotFound, 0));
    BOOL containsLineBreak = !NSEqualRanges([s rangeOfString:@"\n"], NSMakeRange(NSNotFound, 0));

    if (containsQuotes) {
        escapedString = [escapedString stringByReplacingOccurrencesOfString:@"\"" withString:@"\"\""];
    }

    if (containsSeperator || containsLineBreak) {
        escapedString = [NSString stringWithFormat:@"\"%@\"", escapedString];
    }

    return escapedString;
}

Before I go and convert this, however, I wanted to ask the community if there is an easier way now that we're in Swift 2. Have any interesting/new changes occurred for strings that I might want to consider in favor of "Swiftifying" the above code? I did some Googling but nothing jumped out at me and I want to really make sure I do a good job here. :-)

Thanks!

Answer 1

You could reduce your code and save it as a String extension:

extension String {
    func escapeString() -> String {
        var newString = self.stringByReplacingOccurrencesOfString("\"", withString: "\"\"")
        if newString.containsString(",") || newString.containsString("\n") {
            newString = String(format: "\"%@\"", newString)
        }

        return newString
    }
}

Also few tests:

var test1 = String("Test")
test1.escapeString() // produces Test

var test2 = String("Test\n")
test2.escapeString() // produces "Test\n"

var test3 = String("Test, Test2")
test3.escapeString() // produces "Test, Test2"