Replace PR #551 change using fatalError() (#563)

scenee · web-flow · commit 4dd52b1790a9 · 2022-09-07T20:35:50.000+09:00
This resolves issue #561. Instead of continuing to work a modal presentation transition even if a panel state is not .hidden, this library calls fatalError as a programmer error on the occasion.
diff --git a/Sources/Transitioning.swift b/Sources/Transitioning.swift
@@ -99,15 +99,15 @@ class ModalPresentTransition: NSObject, UIViewControllerAnimatedTransitioning {
             return animator
         }
 
-        // Ensure the current(initial) state is hidden. Because `fpc.transitionAnimator` can be nil if not.
-        fpc.move(to: .hidden, animated: false)
-
         fpc.suspendTransitionAnimator(true)
         fpc.show(animated: true) { [weak fpc] in
             fpc?.suspendTransitionAnimator(false)
             transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
         }
-        return fpc.transitionAnimator!
+        guard let transitionAnimator = fpc.transitionAnimator else {
+            fatalError("The panel state must be `hidden` but it is `\(fpc.state)`")
+        }
+        return transitionAnimator
     }
 
     func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {

Original file line number	Diff line number	Diff line change
`@@ -99,15 +99,15 @@ class ModalPresentTransition: NSObject, UIViewControllerAnimatedTransitioning {`
`99`	`99`	`return animator`
`100`	`100`	`}`
`101`	`101`
`102`		- // Ensure the current(initial) state is hidden. Because `fpc.transitionAnimator` can be nil if not.
`103`		`- fpc.move(to: .hidden, animated: false)`
`104`		`-`
`105`	`102`	`fpc.suspendTransitionAnimator(true)`
`106`	`103`	`fpc.show(animated: true) { [weak fpc] in`
`107`	`104`	`fpc?.suspendTransitionAnimator(false)`
`108`	`105`	`transitionContext.completeTransition(!transitionContext.transitionWasCancelled)`
`109`	`106`	`}`
`110`		`- return fpc.transitionAnimator!`
	`107`	`+ guard let transitionAnimator = fpc.transitionAnimator else {`
	`108`	+ fatalError("The panel state must be `hidden` but it is `\(fpc.state)`")
	`109`	`+ }`
	`110`	`+ return transitionAnimator`
`111`	`111`	`}`
`112`	`112`
`113`	`113`	`func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {`