由文字生成path后制作写字的动画

在看以下这个开源组件的时候，发现一个非常棒的方法，能够将文字生成path，这样就能够作出用笔写字的效果了。

https://github.com/MP0w/MPParallaxCollection

关键代码：

-(CGPathRef)pathRefFromText

{

NSAttributedString *attributed = self.attributedText;

CGMutablePathRef letters = CGPathCreateMutable();

CTLineRef line = CTLineCreateWithAttributedString((__bridge CFAttributedStringRef)attributed);

CFArrayRef runArray = CTLineGetGlyphRuns(line);

for (CFIndex runIndex = 0; runIndex < CFArrayGetCount(runArray); runIndex++)

{

CTRunRef run = (CTRunRef)CFArrayGetValueAtIndex(runArray, runIndex);

CTFontRef runFont = CFDictionaryGetValue(CTRunGetAttributes(run), kCTFontAttributeName);

for (CFIndex runGlyphIndex = 0; runGlyphIndex < CTRunGetGlyphCount(run); runGlyphIndex++)

{

CFRange thisGlyphRange = CFRangeMake(runGlyphIndex, 1);

CGGlyph glyph;

CGPoint position;

CTRunGetGlyphs(run, thisGlyphRange, &glyph);

CTRunGetPositions(run, thisGlyphRange, &position);

CGPathRef letter = CTFontCreatePathForGlyph(runFont, glyph, NULL);

CGAffineTransform t = CGAffineTransformMakeTranslation(position.x, position.y);

CGPathAddPath(letters, &t, letter);

CGPathRelease(letter);

}

}

UIBezierPath *path = [UIBezierPath bezierPathWithCGPath:letters];

CGRect boundingBox = CGPathGetBoundingBox(letters);

CGPathRelease(letters);

CFRelease(line);

[path applyTransform:CGAffineTransformMakeScale(1.0, -1.0)];

[path applyTransform:CGAffineTransformMakeTranslation(0.0, boundingBox.size.height)];

if (self.reversedAnimation) {

return [[path bezierPathByReversingPath] CGPath];

}

return [path CGPath];

}