代码中潜在的内存泄漏 [英] Potential memory leak in code

问题描述

在我正在开发的应用程序中，需要定期轮询设备的数据，如加速度，陀螺仪和运动。我编写了以下类来处理所有相关任务（我也使用第三方库 SOMotionDetector 检测设备是否正在移动。如果只是那时，我调用 didReceiveAcceleration 委托方法。

In an app I'm working on, there is a requirement to periodically poll for device's data like acceleration, gyro and motion. I wrote the following class to handle all the related tasks (I also use the third-party library SOMotionDetector to detect whether the device is moving. if only then, I call the didReceiveAcceleration delegate method).

import CoreMotion
import Foundation
import SOMotionDetector

protocol MotionManagerDelegate: class {
    func didReceiveAcceleration(_ acceleration: (x: Double, y: Double, z: Double))
    func didReceiveGyro(_ gyro: (x: Double, y: Double, z: Double))
    func didReceiveMotion(_ motion: (x: Double, y: Double, z: Double, w: Double))
}

class MotionManager: NSObject {

    weak var delegate: MotionManagerDelegate?

    fileprivate let motionDetector = SOMotionDetector.sharedInstance()
    fileprivate let accelerationCaptureInterval: TimeInterval = 0.02
    fileprivate let gyroCaptureInterval: TimeInterval = 1
    fileprivate var lastAcceleration: (x: Double, y: Double, z: Double) = (x: 0.0, y: 0.0, z: 0.0)
    fileprivate var isMoving: Bool = false
    fileprivate var motionManager: CMMotionManager!

    override init() {
        super.init()

        motionManager = CMMotionManager()
        motionManager.gyroUpdateInterval = gyroCaptureInterval
        motionManager.accelerometerUpdateInterval = accelerationCaptureInterval
        motionManager.deviceMotionUpdateInterval = gyroCaptureInterval
        motionDetector?.useM7IfAvailable = true
    }

    func startCapturing() throws {
        motionManager.startGyroUpdates(to: OperationQueue()) { gyroData, error in
            if let rotation = gyroData?.rotationRate {
                let gyro = (x: rotation.x, y: rotation.y, z: rotation.z)
                self.delegate?.didReceiveGyro(gyro)
            } else {
                let gyro = (x: 0.0, y: 0.0, z: 0.0)
                self.delegate?.didReceiveGyro(gyro)
            }
        }

        motionDetector?.motionTypeChangedBlock = { motionType in
            if motionType == MotionTypeNotMoving {
                self.isMoving = false
            } else {
                self.isMoving = true
            }
        }
        motionDetector?.startDetection()

        motionManager.startAccelerometerUpdates(to: OperationQueue()) { accelerometerData, error in
            var x = 0.0
            var y = 0.0
            var z = 0.0
            if let acceleration = accelerometerData?.acceleration {
                x = acceleration.x
                y = acceleration.y
                z = acceleration.z
            }

            if self.isMoving {
                if let delegate = self.delegate {
                    delegate.didReceiveAcceleration((x: x, y: y, z: z))
                }
            }
        }

        motionManager.startDeviceMotionUpdates(to: OperationQueue()) { motionData, error in
            if let quaternion = motionData?.attitude.quaternion {
                let motion = (x: quaternion.x, y: quaternion.y, z: quaternion.z, w: quaternion.w)
                self.delegate?.didReceiveMotion(motion)
            }
        }
    }

    func stopCapturing() {
        motionManager.stopGyroUpdates()
        motionManager.stopAccelerometerUpdates()
        motionManager.stopDeviceMotionUpdates()
        motionDetector?.stopDetection()
    }
}

这很好用。但我得到随机崩溃报告，说代码中存在内存泄漏/堆损坏。由于我无法连接调试器并随着手机上运行的应用程序移动，我无法确定这种情况发生的位置。

This works fine. But I get random crash reports saying there is a memory leak/heap corruption in the code. Since I can't attach the debugger and move about with the app running on the phone, I can't pinpoint where this is occurring.

我非常感谢任何人帮助搞清楚有问题的代码可能是什么。我的上述代码是否容易出现保留周期等问题？

I'd greatly appreciate any help figuring out what the problematic code might be. Is any of my code above prone to issues like retain cycles?

推荐答案

您在自我保留周期。
您在块内强烈捕获 self 但 self 保留这些块和变量..

You have retain cycles on self. You are capturing self strongly inside your blocks but self is retaining those blocks and variables..

示例：

class MotionManager: NSObject {
   override init() {
        super.init()

        motionManager = CMMotionManager() //retains motionManager..
    }

    func usage() {
        motionManager.execute({ foo in
            self.blah(foo);  //capturing self strongly in motionManager block.. motionManager is retained by self.. retain cycle..
        })
    }
}

你需要使用弱自我<块中捕获帧中的$ code>或无主自我。

class MotionManager: NSObject {
   override init() {
        super.init()

        motionManager = CMMotionManager() //retains motionManager..
    }

    func usage() {
        motionManager.execute({ [weak self] (foo) in
            self?.blah(foo);  //Doesn't retain self. Fixed :D
        })
    }
}

做点什么喜欢：

class MotionManager: NSObject {

    weak var delegate: MotionManagerDelegate?

    fileprivate let motionDetector = SOMotionDetector.sharedInstance()
    fileprivate let accelerationCaptureInterval: TimeInterval = 0.02
    fileprivate let gyroCaptureInterval: TimeInterval = 1
    fileprivate var lastAcceleration: (x: Double, y: Double, z: Double) = (x: 0.0, y: 0.0, z: 0.0)
    fileprivate var isMoving: Bool = false

    fileprivate var motionManager: CMMotionManager!


    override init() {
        super.init()

        motionManager = CMMotionManager()
        motionManager.gyroUpdateInterval = gyroCaptureInterval
        motionManager.accelerometerUpdateInterval = accelerationCaptureInterval
        motionManager.deviceMotionUpdateInterval = gyroCaptureInterval

        motionDetector?.useM7IfAvailable = true
    }

    func startCapturing() throws {
        motionManager.startGyroUpdates(to: OperationQueue()) { [weak self] (gyroData, error) in
            if let rotation = gyroData?.rotationRate {
                let gyro = (x: rotation.x, y: rotation.y, z: rotation.z)
                self?.delegate?.didReceiveGyro(gyro)
            } else {
                let gyro = (x: 0.0, y: 0.0, z: 0.0)
                self?.delegate?.didReceiveGyro(gyro)
            }
        }

        motionDetector?.motionTypeChangedBlock = { [weak self] (motionType) in
            if motionType == MotionTypeNotMoving {
                self?.isMoving = false
            } else {
                self?.isMoving = true
            }
        }

        motionDetector?.startDetection()

        motionManager.startAccelerometerUpdates(to: OperationQueue()) { [weak self] (accelerometerData, error) in
            var x = 0.0
            var y = 0.0
            var z = 0.0
            if let acceleration = accelerometerData?.acceleration {
                x = acceleration.x
                y = acceleration.y
                z = acceleration.z
            }

            if (self?.isMoving)! {
                if let delegate = self?.delegate {
                    delegate.didReceiveAcceleration((x: x, y: y, z: z))
                }
            }
        }

        motionManager.startDeviceMotionUpdates(to: OperationQueue()) { [weak self] (motionData, error) in
            if let quaternion = motionData?.attitude.quaternion {
                let motion = (x: quaternion.x, y: quaternion.y, z: quaternion.z, w: quaternion.w)
                self?.delegate?.didReceiveMotion(motion)
            }
        }
    }

    func stopCapturing() {
        motionManager.stopGyroUpdates()
        motionManager.stopAccelerometerUpdates()
        motionManager.stopDeviceMotionUpdates()
        motionDetector?.stopDetection()
    }
}

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