用UIBezierPath单行绘制字母（文本）

Question

我使用this和this作为参考。我是使用UIBezierPath的新手，我想在我使用的字符（字母）代码上绘制路径如下。

CGMutablePathRef letters = CGPathCreateMutable();

CTFontRef font = CTFontCreateWithName(CFSTR("Courier New"), 200.0f, NULL);
NSDictionary *attrs = [NSDictionary dictionaryWithObjectsAndKeys:CFBridgingRelease(font), kCTFontAttributeName,nil];
NSAttributedString *attrString = [[NSAttributedString alloc] initWithString:@"B"
                                                                 attributes:attrs];
CTLineRef line = CTLineCreateWithAttributedString((CFAttributedStringRef)attrString);
CFArrayRef runArray = CTLineGetGlyphRuns(line);

// for each RUN
for (CFIndex runIndex = 0; runIndex < CFArrayGetCount(runArray); runIndex++)
{
    // Get FONT for this run
    CTRunRef run = (CTRunRef)CFArrayGetValueAtIndex(runArray, runIndex);
    CTFontRef runFont = CFDictionaryGetValue(CTRunGetAttributes(run), kCTFontAttributeName);

    // for each GLYPH in run
    for (CFIndex runGlyphIndex = 0; runGlyphIndex < CTRunGetGlyphCount(run); runGlyphIndex++)
    {
        // get Glyph & Glyph-data
        CFRange thisGlyphRange = CFRangeMake(runGlyphIndex, 1);
        CGGlyph glyph;
        CGPoint position;
        CTRunGetGlyphs(run, thisGlyphRange, &glyph);
        CTRunGetPositions(run, thisGlyphRange, &position);

        // Get PATH of outline
        {
            CGPathRef letter = CTFontCreatePathForGlyph(runFont, glyph, NULL);
            CGAffineTransform t = CGAffineTransformMakeTranslation(position.x, position.y);
            CGPathAddPath(letters, &t, letter);
            CGPathRelease(letter);
        }
    }
}
CFRelease(line);

UIBezierPath *path = [UIBezierPath bezierPath];
[path moveToPoint:CGPointZero];
[path appendPath:[UIBezierPath bezierPathWithCGPath:letters]];

CGPathRelease(letters);
CFRelease(font);

NSLog(@"==> %@",path);

// Creates layer
CAShapeLayer *pathLayer = [CAShapeLayer layer];
pathLayer.frame = drawingView.bounds;
pathLayer.bounds = CGPathGetBoundingBox(path.CGPath);
//pathLayer.backgroundColor = [[UIColor yellowColor] CGColor];
pathLayer.geometryFlipped = NO;
pathLayer.path = path.CGPath;
pathLayer.strokeColor = [[UIColor blackColor] CGColor];
pathLayer.fillColor = nil;
pathLayer.lineWidth = 3.0f;
pathLayer.lineJoin = kCALineJoinBevel;

[drawingView.layer addSublayer:pathLayer];

self.pathLayer = pathLayer;


// Add pointer
UIImage *penImage = [UIImage imageNamed:@"hand.png"];
CALayer *penLayer = [CALayer layer];
penLayer.contents = (id)penImage.CGImage;
penLayer.anchorPoint = CGPointMake(0.35f, 0.98f);
penLayer.frame = CGRectMake(0.0f, 0.0f, penImage.size.width, penImage.size.height);
[pathLayer addSublayer:penLayer];
self.penLayer = penLayer;


CABasicAnimation *pathAnimation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];
pathAnimation.duration = 5.0;
pathAnimation.fromValue = [NSNumber numberWithFloat:0.0f];
pathAnimation.toValue = [NSNumber numberWithFloat:1.0f];
[self.pathLayer addAnimation:pathAnimation forKey:@"strokeEnd"];

CAKeyframeAnimation *penAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
penAnimation.duration = 5.0;
penAnimation.path = self.pathLayer.path;
penAnimation.calculationMode = kCAAnimationPaced;
penAnimation.delegate = self;

[self.penLayer addAnimation:penAnimation forKey:@"position"];

此代码以双线形式绘制后者，如下图

相反，我想在单行中绘制后者，如下图

并且手应该在字体的中心而不是边框​​上绘制线条。