swift下使用timer防止crash

• 定義:

// Timer Suspend 狀態(tài)記錄
private var isSusspended: Bool = true
private lazy var autoLearnTimer: DispatchSourceTimer? = {
        let timer: DispatchSourceTimer = DispatchSource.makeTimerSource(flags: .strict, queue: DispatchQueue.global())
        timer.schedule(deadline: .now(), repeating: requestTimeInterVal)
        timer.setEventHandler { [weak self] in
            self?.loop()
        }
        return timer
    }()

• 開始、暫停和銷毀

// MARK: timer 接口
extension ViewController {
    private func startTimer() {
        if isSusspended {
            self.autoLearnTimer?.resume()
        }
        isSusspended = false
    }

    private func stopTimer() {
        if isSusspended {
            return
        }
        isSusspended = true
        DispatchQueue.main.async {
            self.autoLearnTimer?.suspend()
        }
        print("停止定時器")
    }
    private func releaseTimer() {
        if isSusspended {
            self.autoLearnTimer?.resume()
        }
        self.autoLearnTimer?.cancel()
    }
}

deinit {
        releaseTimer()
    }