Determine when CTLine is result of a line break

Question

I'm trying to determine if a CTLineRef is the result of a line break. I'm using CTFramesetterCreateFrame to handle all of the line breaking logic (I'm not manually creating the line breaks). I have an idea of how I can do this, but I'm hoping there's some type of meta-data on the CTLineRef that says specifically if it is the result of a new line break.

Example:

Original:

This is a really long line that goes on for a while.

After CTFramesetterCreateFrame applies line breaking:

This is a really long line that
goes on for a while.

So I want to determine if the 'goes on for a while' is the result of a line break.

Answer 1

I ended up using CTLineGetStringRange(CTLineRef). Just for clarity; This will return the location within your backing string that the CTLineRef represents. After that it was a simple comparison between the CFRange.location, returned by CTLineGetStringRange, to my line's location. YMMV depending on how you get a particular line's location. I have a specialized class I use to get this information (more below).

Here's some code:

NSUInteger totalLines = 100; // Total number of lines in document.
NSUInteger numVisibleLines = 30; // Number of lines that can fit in the view port.
NSUInteger fromLineNumber = 0; // 0 indexed line number. Add + 1 to get the actual line number

NSUInteger numFormatChars = [[NSString stringWithFormat:@"%d", totalLines] length];
NSString *numFormat = [NSString stringWithFormat:@"%%%dd\n", numFormatChars];
NSMutableString *string = [NSMutableString string];
NSArray *lines = (NSArray *)CTFrameGetLines(textFrame);

for (NSUInteger i = 0; i < numVisibleLines; ++i)
{
    CTLineRef lineRef = (CTLineRef)[lines objectAtIndex:i];
    CFRange range = CTLineGetStringRange(lineRef);

    // This is the object I was referring to that provides me with a line's
    // meta-data. The _document is an instance of a specialized class I use to store
    // meta-data about the document which includes where keywords, variables,
    // numbers, etc. are located within the document. (fyi, this is for a text editor)
    NSUInteger lineLocation = [_document indexOfLineNumber:fromLineNumber];

    // Append the line number.
    if (lineLocation == range.location)
    {
        [string appendFormat:numFormat, actualLineNumber];
        actualLineNumber++;
        fromLine++;
    }
    // This is a continuation of a previous line (wrapped line).
    else
    {
        [string appendString:@"\n"];
    }
}

FYI, I didn't up any of the answers because I already knew the CTLineGetStringRange API call existed. I was hoping there was an API call that provided me with a boolean value or something that would indicate that a particular CTLineRef was a continuation of a previous line or not.