在方向改變之前執行一個功能

Question

當方向改變時，是否可以執行一個功能並等待它完成執行然後執行旋轉？類似的東西：

override func viewWillTransitionToSize(size: CGSize, withTransitionCoordinator coordinator: UIViewControllerTransitionCoordinator) { 
     super.viewWillTransitionToSize(size, withTransitionCoordinator: coordinator) 

     doStuff() 

     // block until doStuff is done 
     weak var weakSelf = self 
     coordinator.animateAlongsideTransition({ (UIViewControllerTransitionCoordinatorContext) -> Void in 

      }, completion: { (UIViewControllerTransitionCoordinatorContext) -> Void in 

     }) 
    } 

Answer 1

斯威夫特3

func doStuff(check:(_ Check : Bool)->Void){ 

    check(true) 
} 

和內部viewWillTransitionToSize FUNC：

doStuff { (myCheck) in 
     if myCheck{ 

      // do something 
     } 
    }