iOS: Why the animation runs well with CABasicAnimation but looks weird with animateWithDuration? -

here's simple demo rotating image view animation.

class viewcontroller: uiviewcontroller {      @iboutlet weak var imageview: uiimageview!      @ibaction func left() {         animatewithtransform(catransform3dmakerotation(cgfloat(m_pi_4), 0, 0, 1))     }      @ibaction func right() {         animatewithtransform(catransform3dmakerotation(cgfloat(-m_pi_4), 0, 0, 1))     }      func animatewithtransform(transform: catransform3d) {         uiview.animatewithduration(1) {             self.imageview.layer.transform = transform         }     } } 

the animation runs smoothly. update right() to:

@ibaction func right() {     animatewithtransform(catransform3dmakerotation(cgfloat(-m_pi_4), 0, 1, 0)) } 

tap left right, animation not smooth more. image view jumps angle before starting animation. why's that?

update animatewithtransform() use cabasicanimation instead:

func animatewithtransform(transform: catransform3d) {     let animation = cabasicanimation(keypath: "transform")     animation.duration = 1     animation.fromvalue = nsvalue(catransform3d: imageview.layer.transform)     animation.tovalue = nsvalue(catransform3d: transform)     animation.timingfunction = camediatimingfunction(name: kcamediatimingfunctioneasein)     imageview.layer.addanimation(animation, forkey: nil)      imageview.layer.transform = transform } 

the animation fine again.

so question why can't use animatewithduration here. bug? thanks.

---- update ---------------------------------

btw, image view centered constraints. constraint issue, i'm not sure.

i had same problem, reason animating catransform, done on layer not on view, why uiview.animatewithduration not respond it