ios - How to set a weak reference to a closure/function in Swift? -

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in hmsegmentedcontrol, i'd set segmentedcontrol.indexchangeblock instance method handle action. official example is: https://github.com/heshammegid/hmsegmentedcontrol/blob/master/hmsegmentedcontrolexample/hmsegmentedcontrolexample/viewcontroller.m (line 63 ~ 68), that's objective-c.

in swift, functions first class citizens. wanna set instance method block property.
code lead circular reference, seems should define weak reference: 

class examplevc: uiviewcontroller {     var segmentedcontrolindex: int = 0      override func viewdidload() {       let segmentedcontrol3 = hmsegmentedcontrol(sectionimages: ... , sectionselectedimages: ... )       segmentedcontrol3.frame = ...       segmentedcontrol3.indexchangeblock = someinstancemethod     }      func someinstancemethod(index: int) {       segmentedcontrolindex = index     } }

however, cannot define weak reference non-class type. can do? legal this?

instead of defining weak reference closure, should use "capture list" in closure.

segmentedcontrol3.indexchangeblock = { [unowned self] in self.someinstancemethod($0) }

as far know, way avoid strong reference cycles.


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