Simple CoreText with CTLineDraw and CTRunDraw

gistfile1.m

    CGContextRef context = UIGraphicsGetCurrentContext();
    
    // Flip the coordinate system
    CGContextSetTextMatrix(context, CGAffineTransformIdentity);
    CGContextTranslateCTM(context, 0, self.bounds.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);
    
    NSDictionary *attrs = @{NSFontAttributeName: [UIFont systemFontOfSize:20],
                            NSForegroundColorAttributeName: [UIColor blueColor],
                            NSUnderlineStyleAttributeName: @(NSUnderlineStyleSingle),
                            };
    
    // Make an attributed string
    NSAttributedString *attributedString = [[NSAttributedString alloc] initWithString:@"Hello CoreText!" attributes:attrs];
    CFAttributedStringRef attributedStringRef = (CFAttributedStringRef)attributedString;
    
    // Simple CoreText with CTFrameDraw
    CTFramesetterRef framesetter =  CTFramesetterCreateWithAttributedString(attributedStringRef);
    CGPathRef path = CGPathCreateWithRect(self.bounds,NULL);
    CTFrameRef frame = CTFramesetterCreateFrame(framesetter,CFRangeMake(0, 0),path,NULL);
    //CTFrameDraw(frame, context);
    
    // You can comment the line 'CTFrameDraw' and use the following lines
    // draw with CTLineDraw
    CFArrayRef lines = CTFrameGetLines(frame);
    CGPoint lineOrigins[CFArrayGetCount(lines)];
    CTFrameGetLineOrigins(frame, CFRangeMake(0, 0), lineOrigins);
    for (int i = 0; i < CFArrayGetCount(lines); i++) {
        CTLineRef line = CFArrayGetValueAtIndex(lines, i);
        CGContextSetTextPosition(context,  lineOrigins[i].x, lineOrigins[i].y);
        CTLineDraw(line, context);
        
        // You can comment the line 'CTLineDraw' and use the following lines
        // draw with CTRunDraw
        // use CTRunDraw will lost some attributes like NSUnderlineStyleAttributeName,
        // so you need draw it by yourself
        /*CFArrayRef runs = CTLineGetGlyphRuns(line);
        for (int j = 0; j < CFArrayGetCount(runs); j++) {
            CTRunRef run = CFArrayGetValueAtIndex(runs, j);
            CTRunDraw(run, context, CFRangeMake(0, 0));
        }*/
    }