ios - CAShapeLayer Animation without having to update the path -

when animating cashapelayer, necessary keep updating path of layer, or there way rely on cabasicanimation alone?

in example below, set 4 circles paths , draw them. want animate them down disappear. after animation has completed however, spring original paths.

    int radius =  halfwidth-30; //the radius distance out centre     trackactive.path = [uibezierpath bezierpathwitharccenter:ciclecenter radius:radius startangle:degreestoradians(circlestart) endangle:degreestoradians(circleend) clockwise:true].cgpath;     circleactive.path = [uibezierpath bezierpathwitharccenter:ciclecenter radius:radius startangle:degreestoradians(circlestart) endangle:degreestoradians(circleend) clockwise:true].cgpath;      radius = halfwidth - 10;     tracknew.path = [uibezierpath bezierpathwitharccenter:ciclecenter radius:radius startangle:degreestoradians(circlestart) endangle:degreestoradians(circleend) clockwise:true].cgpath;     circlenew.path = [uibezierpath bezierpathwitharccenter:ciclecenter radius:radius startangle:degreestoradians(circlestart) endangle:degreestoradians(circleend) clockwise:true].cgpath;      nsarray * layers = @[trackactive, circleactive, tracknew, circlenew];     (cashapelayer * layer in layers){          [catransaction begin];         cabasicanimation * animation = [cabasicanimation animationwithkeypath:@"strokeend"];         animation.duration = 1.0f;         animation.removedoncompletion = false;         animation.fromvalue = @(1.0);         animation.tovalue = @(0.0);         animation.timingfunction = [camediatimingfunction functionwithname:kcamediatimingfunctioneaseineaseout];         [layer addanimation:animation forkey:@"circleanimation"];          [catransaction commit];     } 

i understand can add set new path:

    [catransaction setcompletionblock:^{          //set new path         layer.path = [uibezierpath bezierpathwitharccenter:ciclecenter radius:radius startangle:degreestoradians(circlestart) endangle:degreestoradians(arcend) clockwise:true].cgpath;      }]; 

but prefer avoid keep having update path, , instead rely on animation layer exclusively. possible?

something like: layer.path = animation.path or animation.updatesoriginalpath=true; wishful thinking, not sure.

you can simplify code , omit spring effect:

[catransaction begin]; [catransaction setanimationduration:1.0]; [catransaction setanimationtimingfunction: kcamediatimingfunctioneaseineaseout]; layer.strokeend = 0.0; [catransaction commit]; 

the transaction create , add implicit animation object you.