文字渐渐显示效果

#import "DMAnimationLayer.h" @interface DMAnimationLayer() @property (nonatomic, retain) CAShapeLayer *pathLayer; @property (nonatomic, retain) CALayer *penLayer; @end @implementation DMAnimationLayer +(void)createAnimationLayerWithString:(NSString*)string andRect:(CGRect)rect andView:(UIView *)view andFont:(UIFont*)ui_font andStrokeColor:(UIColor*)color { DMAnimationLayer * animationLayer = [DMAnimationLayer layer]; animationLayer.frame = rect; [view.layer addSublayer:animationLayer]; if (animationLayer.pathLayer != nil) { [animationLayer.penLayer removeFromSuperlayer]; [animationLayer.pathLayer removeFromSuperlayer]; animationLayer.pathLayer = nil; animationLayer.penLayer = nil; } CTFontRef font =CTFontCreateWithName((CFStringRef)ui_font.fontName, ui_font.pointSize, NULL); CGMutablePathRef letters = CGPathCreateMutable(); //这里设置画线的字体和大小 NSDictionary *attrs = [NSDictionary dictionaryWithObjectsAndKeys: (__bridge id)font, kCTFontAttributeName, nil]; NSAttributedString *attrString = [[NSAttributedString alloc] initWithString:string 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++) { 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); } } } CFRelease(line); UIBezierPath *path = [UIBezierPath bezierPath]; [path moveToPoint:CGPointZero]; [path appendPath:[UIBezierPath bezierPathWithCGPath:letters]]; CGPathRelease(letters); CFRelease(font); // CAShapeLayer *pathLayer = [CAShapeLayer layer]; pathLayer.frame = CGRectMake(0, 0, rect.size.width, rect.size.height -230); pathLayer.bounds = CGPathGetBoundingBox(path.CGPath); pathLayer.geometryFlipped = YES; pathLayer.path = path.CGPath; pathLayer.strokeColor = [color CGColor]; pathLayer.fillColor = nil; pathLayer.lineWidth = 1.0f; pathLayer.lineJoin = kCALineJoinBevel; [animationLayer addSublayer:pathLayer]; animationLayer.pathLayer = pathLayer; CABasicAnimation *pathAnimation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"]; pathAnimation.duration = 5.0; pathAnimation.fromValue = [NSNumber numberWithFloat:0.0f]; pathAnimation.toValue = [NSNumber numberWithFloat:1.0f]; [animationLayer.pathLayer addAnimation:pathAnimation forKey:@"strokeEnd"]; CAKeyframeAnimation *penAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"]; penAnimation.duration = 5.0; penAnimation.path = animationLayer.pathLayer.path; penAnimation.calculationMode = kCAAnimationPaced; penAnimation.delegate = animationLayer; [animationLayer.penLayer addAnimation:penAnimation forKey:@"position"]; } - (void) animationDidStop:(CAAnimation *)anim finished:(BOOL)flag { self.penLayer.hidden = YES; } @end #import "DMAnimationLayer.h" @interface DMAnima