CAShapeLayer animation doesn't stay on screen but disappears - ios

Question

I'm trying to draw a animated circle but every segment needs to have another color. Now everything works except that my piece that is just drawed before I call the method again disappears so only the last part stays. I don't want that, I want that after 4 times a whole circle is drawn in different color strokes.
How can I fix this that it doesn't disappears?
This is my init code:
- (void)_initCircle {
_circle = [CAShapeLayer layer];
_radius = 100;
// Make a circular shape
_circle.path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, 2.0 * _radius, 2.0 * _radius) cornerRadius:_radius].CGPath;
// Center the shape in self.view
_circle.position = CGPointMake(CGRectGetMidX(self.view.frame) - _radius,
CGRectGetMidY(self.view.frame) - _radius);
_circle.fillColor = [UIColor clearColor].CGColor;
_circle.lineWidth = 5;
// Add to parent layer
[self.view.layer addSublayer:_circle];
}
This is my draw piece:
- (void)_drawStrokeOnCircleFrom:(float)start to:(float)end withColor:(UIColor *)color {
// Configure the apperence of the circle
_circle.strokeColor = color.CGColor;
_circle.strokeStart = start;
_circle.strokeEnd = end;
[CATransaction begin];
// Configure animation
CABasicAnimation *drawAnimation = [CABasicAnimation animationWithKeyPath:#"strokeEnd"];
drawAnimation.duration = 2.0; // "animate over 10 seconds or so.."
drawAnimation.repeatCount = 1.0; // Animate only once..
// Animate from no part of the stroke being drawn to the entire stroke being drawn
drawAnimation.fromValue = [NSNumber numberWithFloat:start];
drawAnimation.toValue = [NSNumber numberWithFloat:end];
// Experiment with timing to get the appearence to look the way you want
drawAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
[CATransaction setCompletionBlock:^{
NSLog(#"Complete animation");
_index++;
if(_index < _votes.count){
_startStroke = _endStroke;
_endStroke += [_votes[_index] floatValue] / _totalListens;
[self _drawStrokeOnCircleFrom:_startStroke to:_endStroke withColor:_colors[_index]];
}
}];
// Add the animation to the circle
[_circle addAnimation:drawAnimation forKey:#"drawCircleAnimation"];
[CATransaction commit];
}

Answer 1

Try setting these values on your CABasicAnimation:
drawAnimation.removedOnCompletion = NO;
drawAnimation.fillMode = kCAFillModeForwards;

Answer 2

That worked for me using "kCAFillModeBoth", both statements are necessary:
//to keep it after finished
animation.removedOnCompletion = false;
animation.fillMode = kCAFillModeBoth;

Answer 3

I solved the problem with extra layers like this:
- (void)_drawStrokeOnCircle {
[self _initCircle];
[CATransaction begin];
for (NSUInteger i = 0; i < 4; i++)
{
CAShapeLayer* strokePart = [[CAShapeLayer alloc] init];
strokePart.fillColor = [[UIColor clearColor] CGColor];
strokePart.frame = _circle.bounds;
strokePart.path = _circle.path;
strokePart.lineCap = _circle.lineCap;
strokePart.lineWidth = _circle.lineWidth;
// Configure the apperence of the circle
strokePart.strokeColor = ((UIColor *)_colors[i]).CGColor;
strokePart.strokeStart = [_segmentsStart[i] floatValue];
strokePart.strokeEnd = [_segmentsEnd[i] floatValue];
[_circle addSublayer: strokePart];
// Configure animation
CAKeyframeAnimation* drawAnimation = [CAKeyframeAnimation animationWithKeyPath: #"strokeEnd"];
drawAnimation.duration = 4.0;
// Animate from no part of the stroke being drawn to the entire stroke being drawn
NSArray* times = #[ #(0.0),
#(strokePart.strokeStart),
#(strokePart.strokeEnd),
#(1.0) ];
NSArray* values = #[ #(strokePart.strokeStart),
#(strokePart.strokeStart),
#(strokePart.strokeEnd),
#(strokePart.strokeEnd) ];
drawAnimation.keyTimes = times;
drawAnimation.values = values;
drawAnimation.removedOnCompletion = NO;
drawAnimation.fillMode = kCAFillModeForwards;
// Experiment with timing to get the appearence to look the way you want
drawAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
[strokePart addAnimation: drawAnimation forKey: #"drawCircleAnimation"];
}
[CATransaction commit];
}
- (void)_initCircle {
[_circle removeFromSuperlayer];
_circle = [CAShapeLayer layer];
_radius = 100;
// Make a circular shape
_circle.path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, 2.0 * _radius, 2.0 * _radius) cornerRadius:_radius].CGPath;
// Center the shape in self.view
_circle.position = CGPointMake(CGRectGetMidX(self.view.frame) - _radius,
CGRectGetMidY(self.view.frame) - _radius);
_circle.fillColor = [UIColor clearColor].CGColor;
_circle.lineWidth = 5;
// Add to parent layer
[self.view.layer addSublayer:_circle];
}

Answer 4

SWIFT 4, Xcode 11:
let strokeIt = CABasicAnimation(keyPath: "strokeEnd")
let timeLeftShapeLayer = CAShapeLayer()
and in your viewDidLoad
override func viewDidLoad() {
super.viewDidLoad()
drawTimeLeftShape()
strokeIt.fillMode = CAMediaTimingFillMode.forwards
strokeIt.isRemovedOnCompletion = false
strokeIt.fromValue = 0
strokeIt.toValue = 1
strokeIt.duration = 2
timeLeftShapeLayer.add(strokeIt, forKey: nil)
}
and by UIBezierPathcreate function to draw circle:
func drawTimeLeftShape() {
timeLeftShapeLayer.path = UIBezierPath(
arcCenter: CGPoint(x: myView.frame.midX , y: myView.frame.midY),
radius: myView.frame.width / 2,
startAngle: -90.degreesToRadians,
endAngle: 270.degreesToRadians,
clockwise: true
).cgPath
timeLeftShapeLayer.strokeColor = UIColor.red.cgColor
timeLeftShapeLayer.fillColor = UIColor.clear.cgColor
timeLeftShapeLayer.lineWidth = 1
timeLeftShapeLayer.strokeEnd = 0.0
view.layer.addSublayer(timeLeftShapeLayer)
}