I'm looking to add some highlighting to my Core Text View, and implemented the
following which comes straight from Apple's SimpleTextInput code example
(https://developer.apple.com/library/iOs/#samplecode/SimpleTextInput/Introduction/Intro.html):
// Helper method for drawing the current selection range (as a simple filled
rect)
- (void)drawRangeAsSelection:(NSRange)selectionRange
{
// If not in editing mode, we do not draw selection rects
if (!self.editing)
return;
// If selection range empty, do not draw
if (selectionRange.length == 0 || selectionRange.location == NSNotFound)
return;
// set the fill color to the selection color
[[SimpleCoreTextView selectionColor] setFill];
// Iterate over the lines in our CTFrame, looking for lines that
intersect
// with the given selection range, and draw a selection rect for each
intersection
NSArray *lines = (NSArray *) CTFrameGetLines(_frame);
for (int i = 0; i < [lines count]; i++) {
CTLineRef line = (CTLineRef) [lines objectAtIndex:i];
CFRange lineRange = CTLineGetStringRange(line);
NSRange range = NSMakeRange(lineRange.location, lineRange.length);
NSRange intersection = [self RangeIntersection:range
withSecond:selectionRange];
if (intersection.location != NSNotFound && intersection.length > 0) {
// The text range for this line intersects our
selection range
CGFloat xStart = CTLineGetOffsetForStringIndex(line,
intersection.location, NULL);
CGFloat xEnd = CTLineGetOffsetForStringIndex(line,
intersection.location + intersection.length, NULL);
CGPoint origin;
// Get coordinate and bounds information for the
intersection text range
CTFrameGetLineOrigins(_frame, CFRangeMake(i, 0), &origin);
CGFloat ascent, descent;
CTLineGetTypographicBounds(line, &ascent, &descent, NULL);
<<<<<<<<<=========================== BOOM!
// Create a rect for the intersection and draw it with
selection color
CGRect selectionRect = CGRectMake(xStart, origin.y - descent, xEnd
- xStart, ascent + descent);
UIRectFill(selectionRect);
}
}
}
But every time, I get an EXC_BAD_ACCESS error for the
CTLineGetTypographicBounds() call. I triple checked that _frame and line are
valid at this point, and the debugger output shows what it is supposed to be
(correct string, attributes, etc).
Here's the output from bt:
(lldb) bt
* thread #1: tid = 0x1c03, 0x0027bbd0 CoreText`CTLineGetTypographicBounds + 29,
stop reason = EXC_BAD_ACCESS (code=2, address=0x60)
frame #0: 0x0027bbd0 CoreText`CTLineGetTypographicBounds + 29
frame #1: 0x000469a4 MyApp`-[MyView drawRangeAsSelection:](self=0x4576f000,
_cmd=0x00000000, selectionRange=(null)) + 628 at MyView.m:461
Any suggestions why this could be happening?
Thanks,
- Koen.
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