UIFeedback触觉引擎被调用的次数多于被激活的次数

Question

我使用UIFeedback Haptic Engine与swift 2.3像:

let generator = UINotificationFeedbackGenerator()
generator.notificationOccurred(.Warning)

和

let generator = UIImpactFeedbackGenerator(style: .Heavy)
generator.impactOccurred()

今天我得到了一个新的错误，像这样，找不到问题。你知道吗?

UIFeedbackHapticEngine _deactivate] called more times than the feedback engine was activated

细节:

Fatal Exception: NSInternalInconsistencyException
0  CoreFoundation                 0x1863e41c0 __exceptionPreprocess
1  libobjc.A.dylib                0x184e1c55c objc_exception_throw
2  CoreFoundation                 0x1863e4094 +[NSException raise:format:]
3  Foundation                     0x186e6e82c -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:]
4  UIKit                          0x18cc43fb8 -[_UIFeedbackEngine _deactivate]
5  UIKit                          0x18cad781c -[UIFeedbackGenerator __deactivateWithStyle:]

Answer 1

UIImpactFeedbackGenerator不是线程安全的，所以请确保同步调用generator.impactOccurred()，而不是在dispatch_async或另一个异步线程中。

Answer 2

调用generator.impactOccurred()会在iOS 11.*上崩溃。你需要在主线程async上调用它。

let generator = UIImpactFeedbackGenerator(style: style)
generator.prepare()
DispatchQueue.main.async {
   generator.impactOccurred()
}

Answer 3

只是为了完成已经给出的答案:您想要做的是拥有一个OperationQueue或DispatchQueue，它们将始终用于调用FeedbackGenerator的函数。请记住，对于您的用例，您可能必须释放生成器，但一个最小的示例将是:

class HapticsService {
    private let hapticsQueue = DispatchQueue(label: "dev.alecrim.hapticQueue", qos: .userInteractive)
    typealias FeedbackType = UINotificationFeedbackGenerator.FeedbackType
    private let feedbackGeneator = UINotificationFeedbackGenerator()
    private let selectionGenerator = UISelectionFeedbackGenerator()
    func prepareForHaptic() {
        hapticsQueue.async {
            self.feedbackGeneator.prepare()
            self.selectionGenerator.prepare()
        }
    }
    func performHaptic(feedback: FeedbackType) {
        hapticsQueue.async {
            self.feedbackGeneator.notificationOccurred(feedback)
        }
    }
    func performSelectionHaptic() {
        hapticsQueue.async {
            self.selectionGenerator.selectionChanged()
        }
    }
}

这基本上解决了我们在生产中相关的崩溃问题。