SLComposeViewController错误=＆gt; LaunchServices：invalidationHandler被调用

Question

我在我的SpriteKit游戏（iOS 8 + Swift）中整合社交分享。一切正常，但我收到以下错误：＆＃34;启动服务：invalidationHandler调用＆＃34;。知道如何修复错误吗？这是我的代码：

func shareWithFacebook() {

    if SLComposeViewController.isAvailableForServiceType(SLServiceTypeFacebook) {
        let facebookSheet = SLComposeViewController(forServiceType: SLServiceTypeFacebook)
        facebookSheet.setInitialText("Test FB post with score of \(score)")
        self.presentViewController(facebookSheet, animated: true, completion: nil)
    } else {
        println("facebook not available")
    }

}

我还尝试在呈现ViewController之前添加一个sourceView，但仍然出错...

facebookSheet.popoverPresentationController?.sourceView = self.view