swift - Use UIView.animateWithDuration inside protocol -

how can use uiview.animatewithduration inside swift protocol? when try use get:

ambiguous reference member 'animatewithduration(_:delay:options:animations:completion:)'

how can reference uiview (animatewithduration static method understand)?

since can not provide implementation inside protocol declaration itself, should reference uiview class inside default implementation. hope 1 of 3 template cases need:

import uikit  protocol someprotocol {     static func animatewithduration(duration: nstimeinterval, delay: nstimeinterval, options: uiviewanimationoptions, animations: () -> void, completion: ((bool) -> void)?)     func animatewithduration(duration: nstimeinterval, delay: nstimeinterval, options: uiviewanimationoptions, animations: () -> void, completion: ((bool) -> void)?)     func somecustomfuncforanimate() }  extension someprotocol {     static func animatewithduration(duration: nstimeinterval, delay: nstimeinterval, options: uiviewanimationoptions, animations: () -> void, completion: ((bool) -> void)?) {         uiview.animatewithduration(duration, delay: delay, options: options, animations: animations, completion: completion)     }     func animatewithduration(duration: nstimeinterval, delay: nstimeinterval, options: uiviewanimationoptions, animations: () -> void, completion: ((bool) -> void)?) {         uiview.animatewithduration(duration, delay: delay, options: options, animations: animations, completion: completion)     }     func somecustomfuncforanimate() {         uiview.animatewithduration(0.2, delay: 1, options: .transitioncrossdissolve, animations: {/*...*/}, completion: nil)     } }