CODEWITHSUNDEEP
iosuibezierpathcabasicanimation
Pataquer
Pataquer

Reputation: 303

CABasicAnimation + UIBezierPath

I'm trying to create a circular bar such the one that you can find around the recording button in the native camera on iOS when you are doing a timelapse.

A circle is created along the animation, and once it is completed is removed again "naturally".

I tried next code:

CAShapeLayer *circle = [CAShapeLayer layer];
circle.path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(self.lapseBtnOutlet.center.x, self.lapseBtnOutlet.center.y) radius:28 startAngle:2*M_PI*0-M_PI_2 endAngle:2*M_PI*1-M_PI_2 clockwise:YES].CGPath;
circle.fillColor = [UIColor clearColor].CGColor;
circle.strokeColor = [UIColor whiteColor].CGColor;
circle.lineWidth = 2.0;

CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];
animation.duration = self.lapseInterval;
animation.removedOnCompletion = NO;
animation.fromValue = @(0);
animation.toValue = @(1);
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
[circle addAnimation:animation forKey:@"drawCircleAnimation"];

But my problem now is that I don't know how to "remove" the line from start-to-end.

I tried with autoreverse property, but it removes the circle from end-to-start instead from start-to-end. Any ideas?

Upvotes: 2

Views: 1475

Answers (1)

rdelmar
rdelmar

Reputation: 104082

You need to animate the strokeStart from 0 to 1, and when the animation finishes, remove the shape layer. 

- (void)viewDidLoad {
    [super viewDidLoad];
    [self performSelector:@selector(animateProperty:) withObject:@"strokeEnd" afterDelay:1];
    [self performSelector:@selector(animateProperty:) withObject:@"strokeStart" afterDelay:3];
}


-(void)animateProperty:(NSString *) prop {
    if (! self.circle) {
        self.circle = [CAShapeLayer layer];
        self.circle.path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(self.lapseBtnOutlet.center.x, self.lapseBtnOutlet.center.y) radius:28 startAngle:2*M_PI*0-M_PI_2 endAngle:2*M_PI*1-M_PI_2 clockwise:YES].CGPath;
        self.circle.fillColor = [UIColor clearColor].CGColor;
        self.circle.strokeColor = [UIColor whiteColor].CGColor;
        self.circle.lineWidth = 2.0;
        [self.view.layer addSublayer:self.circle];
    }

    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:prop];
    animation.delegate = ([prop isEqualToString:@"strokeStart"])? self : nil;
    animation.duration = 1;
    animation.removedOnCompletion = NO;
    animation.fromValue = @0;
    animation.toValue = @1;
    [self.circle addAnimation:animation forKey:prop];
}


-(void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag {
    [self.circle removeFromSuperlayer];
    self.circle = nil;
}

Upvotes: 1

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