[iOS/디버그일지] UIPageViewController의 setPage에서 크래쉬 발생 (*** Assertion failure in -[_UIQueuingScrollView _replaceViews:updatingContents:adjustContentInsets:animated:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit/UIKit-3600..

setViewControllers([viewController], direction: .forward, animated: true, completion: { [weak self] (_) in

    self?.someUIMethod()

})

음.. 크래쉬 발생함

*** Assertion failure in -[_UIQueuingScrollView _replaceViews:updatingContents:adjustContentInsets:animated:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit/UIKit-3600.9.1/_UIQueuingScrollView.m:377

원인은 setViewControllers의 completion 클로져가 메인 스레드에서 수행된다는 보장이 없음.

setViewControllers([viewController], direction: .forward, animated: true, completion: { [weak self] (_) in

    DispatchQueue.main.async {

        self?.someUIMethod()

    }

})

메인 스레드에서 실행해주면 크래쉬 안남 :)