CoreAnimation CAShapeLayer 动画贝塞尔路径

Question

我希望 endAngle 增加，这样看起来时间不多了。

UIBezierPath *path = [UIBezierPath bezierPath];
CAShapeLayer *bezier = [[CAShapeLayer alloc] init];
bezier.path = path.CGPath;

UIGraphicsBeginImageContext(size);
context = UIGraphicsGetCurrentContext();
[path moveToPoint:center];
[path addArcWithCenter:center
                radius:radius
            startAngle:0 - M_PI_2 // zero degrees is east, not north, so subtract pi/2
              endAngle:2 * M_PI * 0.25 - M_PI_2 // ditto
             clockwise:YES];
[path closePath];
CGContextSetFillColorWithColor(context, [AppDelegate colorFromHexString:@"#888888" alpha:0.9].CGColor);
[path fill];
UIImage *requestStatusCircleImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageView *requestStatusCircleImageView = [[UIImageView alloc]initWithImage:requestStatusCircleImage];
requestStatusCircleImageView.layer.rasterizationScale = [UIScreen mainScreen].scale;
requestStatusCircleImageView.layer.shouldRasterize = YES;
requestStatusCircleImageView.translatesAutoresizingMaskIntoConstraints = NO;
[requestStatusCircleContainer addSubview:requestStatusCircleImageView];


 Request Status Circle Image Constraints
[requestStatusCircleContainer addConstraint:[NSLayoutConstraint constraintWithItem:requestStatusCircleImageView attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:requestStatusCircleContainer attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0.0]];
[requestStatusCircleContainer addConstraint:[NSLayoutConstraint constraintWithItem:requestStatusCircleImageView attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:requestStatusCircleContainer attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0.0]];

[self.view.layer addSublayer:bezier];

CABasicAnimation *animateStrokeEnd = [CABasicAnimation animationWithKeyPath:@"endAngle"];
animateStrokeEnd.duration  = 5.0;
animateStrokeEnd.fromValue = [NSNumber numberWithFloat:0.0f];
animateStrokeEnd.toValue   = [NSNumber numberWithFloat:1.0f];
[bezier addAnimation:animateStrokeEnd forKey:@"endAngle"];

如何从 CABasicAnimation 访问 endAngle 参数？

（抱歉代码乱七八糟）

Answer 1

您可以使用presentationLayer获取当前动画值

CGFloat val = [[bezier.presentationLayer valueForKey:@"strokeEnd"] floatValue];