Question

我的应用使用Geojson文件。我使用MapBox SDK将MGLPolyline添加到地图中。但问题是我的文件太大，以至于应用程序崩溃并收到错误：Message from debugger: Terminated due to memory issue。我在第一次循环时面对 66234 对象。我试图将数组块化为新数组，但没有成功。请帮我解决问题。这是我在地图上绘制的代码，这里是我的test project on github use Xcode 8.1 如果有任何不同的第三方可以解决我的问题，也欢迎：

func drawPolyline() {

    // Parsing GeoJSON can be CPU intensive, do it on a background thread
    DispatchQueue.global(qos: .background).async {
        // Get the path for example.geojson in the app's bundle
        let jsonPath = Bundle.main.path(forResource: "KMLMAPNew", ofType: "json")
        let jsonData = NSData(contentsOfFile: jsonPath!)

        do {
            // Load and serialize the GeoJSON into a dictionary filled with properly-typed objects
            guard let jsonDict = try JSONSerialization.jsonObject(with: jsonData! as Data, options: []) as? Dictionary<String, AnyObject>, let features = jsonDict["features"] as? Array<AnyObject> else{return}

            for feature in features {
                guard let feature = feature as? Dictionary<String, AnyObject>, let geometry = feature["geometry"] as? Dictionary<String, AnyObject> else{ continue }

                if geometry["type"] as? String == "LineString" {
                    // Create an array to hold the formatted coordinates for our line
                    var coordinates: [CLLocationCoordinate2D] = []

                    if let locations = geometry["coordinates"] as? Array<AnyObject> {
                        // Iterate over line coordinates, stored in GeoJSON as many lng, lat arrays
                        for location in locations {
                            // Make a CLLocationCoordinate2D with the lat, lng
                            if let location = location as? Array<AnyObject>{
                                let coordinate = CLLocationCoordinate2DMake(location[1].doubleValue, location[0].doubleValue)

                                // Add coordinate to coordinates array
                                coordinates.append(coordinate)
                            }
                        }
                    }

                    let line = MGLPolyline(coordinates: &coordinates, count: UInt(coordinates.count))

                    // Optionally set the title of the polyline, which can be used for:
                    //  - Callout view
                    //  - Object identification
                    line.title = "Crema to Council Crest"

                    // Add the annotation on the main thread
                    DispatchQueue.main.async {
                        // Unowned reference to self to prevent retain cycle
                        [unowned self] in
                        self.mapboxView.addAnnotation(line)
                    }
                }
            }
        }
        catch
        {
            print("GeoJSON parsing failed")
        }
    }
}

编辑：：@ Alessandro Ornano和@fragilecat非常感谢。但这些解决方案仍然无法解决iPad上应用程序的终止问题。我认为很难改变当前的代码以使其正常工作，因为数据太大了。我想我需要另一种适用于大数据的解决方案。就像将数组分块到小数组中一样，然后通过队列加载它们。但我不知道如何开始:(

我向MapBox的支持团队发送电子邮件，询问建议。

Answer 1

这里的问题与有效的内存管理有关。您正在通过json文件加载大量数据。您意识到您需要在后台队列（线程）上完成大部分工作，但问题是如何通过DispatchQueue.main.async函数更新UI。在当前版本的drawPolyline()方法中，在给定第一个循环中的对象数量的情况下，您将在后台队列和主队列之间切换66234次。您也创建了相同数量的CLLocationCoordinate2D数组。

这会导致巨大的内存占用。您没有提到有关如何渲染线条的任何要求。因此，如果我们重构您的drawPolyline()方法以使用CLLocationCoordinate2D数组的实例变量，那么我们只使用一个，然后在更新UI之前处理所有json文件。内存使用量下降到更容易管理的664.6 MB。

当然，渲染可能并不完全符合您的要求，如果是这种情况，您可能希望将CLLocationCoordinate2D数组重组为更合适的数据结构。

以下是您的ViewController课程，其中drawPolyline()被重写为drawPolyline2()

import UIKit
import Mapbox

class ViewController: UIViewController, MGLMapViewDelegate {

@IBOutlet var mapboxView: MGLMapView!


fileprivate var coordinates = [[CLLocationCoordinate2D]]()
fileprivate var jsonData: NSData?

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    mapboxView = MGLMapView(frame: view.bounds)
    mapboxView.autoresizingMask = [.flexibleWidth, .flexibleHeight]

    // mapboxView.setCenter(CLLocationCoordinate2D(latitude: 45.5076, longitude: -122.6736),
    //                             zoomLevel: 11, animated: false)

    mapboxView.setCenter(CLLocationCoordinate2D(latitude: 1.290270, longitude: 103.851959),
                         zoomLevel: 11, animated: false)


    view.addSubview(self.mapboxView)


    mapboxView.delegate = self
    mapboxView.allowsZooming = true

    drawPolyline2()
    //newWay()
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}



func drawPolyline2() {

    DispatchQueue.global(qos: .background).async {

        if let path = Bundle.main.path(forResource: "KMLMAPNew", ofType: "json") {
            let fileURL = URL(fileURLWithPath: path)
            if let data = try? Data(contentsOf: fileURL) {

                do {

                    let dictionary = try JSONSerialization.jsonObject(with: data as Data, options: []) as? Dictionary<String, AnyObject>

                    if let features = dictionary?["features"] as? Array<AnyObject> {

                        print("** START **")

                        for feature in features {
                            guard let feature = feature as? Dictionary<String, AnyObject>, let geometry = feature["geometry"] as? Dictionary<String, AnyObject> else { continue }

                            if geometry["type"] as? String == "LineString" {
                                // Create an array to hold the formatted coordinates for our line

                                if let locations = geometry["coordinates"] as? Array<AnyObject> {
                                    // Iterate over line coordinates, stored in GeoJSON as many lng, lat arrays

                                    var featureCoordinates = [CLLocationCoordinate2D]()

                                    for location in locations {
                                        // Make a CLLocationCoordinate2D with the lat, lng
                                        if let location = location as? Array<AnyObject>{
                                            let coordinate = CLLocationCoordinate2DMake(location[1].doubleValue, location[0].doubleValue)

                                            // Add coordinate to coordinates array
                                            featureCoordinates.append(coordinate)
                                        }
                                    }

                                    // Uncomment if you need to store for later use.
                                    //self.coordinates.append(featureCoordinates)

                                    DispatchQueue.main.async {
                                        let line = MGLPolyline(coordinates: &featureCoordinates, count: UInt(featureCoordinates.count))

                                        // Optionally set the title of the polyline, which can be used for:
                                        //  - Callout view
                                        //  - Object identification
                                        line.title = "Crema to Council Crest"
                                        self.mapboxView.addAnnotation(line)

                                    }


                                }

                            }

                        }

                        print("** FINISH **")

                    }

                } catch {
                    print("GeoJSON parsing failed")
                }
            }
        }
    }
}


func drawSmallListObj(list: [Dictionary<String, AnyObject>]){
    for obj in list{
        //            print(obj)
        if let feature = obj as? Dictionary<String, AnyObject> {
            if let geometry = feature["geometry"] as? Dictionary<String, AnyObject> {
                if geometry["type"] as? String == "LineString" {
                    // Create an array to hold the formatted coordinates for our line
                    var coordinates: [CLLocationCoordinate2D] = []

                    if let locations = geometry["coordinates"] as? Array<AnyObject> {
                        // Iterate over line coordinates, stored in GeoJSON as many lng, lat arrays
                        for location in locations {
                            // Make a CLLocationCoordinate2D with the lat, lng
                            if let location = location as? Array<AnyObject>{
                                let coordinate = CLLocationCoordinate2DMake(location[1].doubleValue, location[0].doubleValue)

                                // Add coordinate to coordinates array
                                coordinates.append(coordinate)
                            }
                        }
                    }

                    let line = MGLPolyline(coordinates: &coordinates, count: UInt(coordinates.count))

                    // Optionally set the title of the polyline, which can be used for:
                    //  - Callout view
                    //  - Object identification
                    line.title = "Crema to Council Crest"

                    // Add the annotation on the main thread
                    DispatchQueue.main.async {
                        // Unowned reference to self to prevent retain cycle
                        [unowned self] in
                        self.mapboxView.addAnnotation(line)
                    }
                }
            }
        }
    }
}
func mapView(_ mapView: MGLMapView, alphaForShapeAnnotation annotation: MGLShape) -> CGFloat {
    // Set the alpha for all shape annotations to 1 (full opacity)
    return 1
}

func mapView(_ mapView: MGLMapView, lineWidthForPolylineAnnotation annotation: MGLPolyline) -> CGFloat {
    // Set the line width for polyline annotations
    return 2.0
}

func mapView(_ mapView: MGLMapView, strokeColorForShapeAnnotation annotation: MGLShape) -> UIColor {
    // Give our polyline a unique color by checking for its `title` property
    if (annotation.title == "Crema to Council Crest" && annotation is MGLPolyline) {
        // Mapbox cyan
        return UIColor(red: 59/255, green:178/255, blue:208/255, alpha:1)
    }
    else
    {
        return UIColor.red
    }
}


}

Answer 2

我从创建内存密集型应用程序中学到的一件事是，每次在循环中创建变量时都必须使用func loopALot() { for _ in 0 ..< 5000 { let image = NSImage(contentsOfFile: filename) } }，如果这些循环很长

查看所有代码并转换

等内容

func loopALot() {
    for _ in 0 ..< 5000 {
      autoreleasepool {
        let image = NSImage(contentsOfFile: filename)
      }
    }
}

到

for

查看各种循环while，db = p1 db = json.load(f)等

这将迫使iOS在循环的每个回合结束时释放变量及其对应的内存使用量，而不是保留变量及其内存使用量，直到函数结束。这将大大减少您的内存使用量。

Answer 3

我在使用pod测试项目时遇到了一些问题，因此我直接从here删除了pod并直接使用Mapbox框架。

我在模拟器和真正的iPad（我的iPad 4 gen。）中首次发布都没有问题，但过了一段时间我也有同样的错误，所以我用以下代码更正了这个代码：

DispatchQueue.main.async {
      // weaked reference to self to prevent retain cycle
      [weak self] in
      guard let strongSelf = self else { return } 
      strongSelf.mapboxView.addAnnotation(line)
}

因为unowned它不足以阻止保留周期。现在看起来效果很好。

希望它有所帮助。

P.S。 （我使用过最新的Mapbox v3.3.6）

更新（评论后）：

因此，首先我将Mapbox框架作为“嵌入式框架”插入我的所有测试。

我已经对你的github项目进行了一些修改，只到ViewController.swift以避免保留周期。的 P.S 即可。我删除注释行以便于阅读：

func drawPolyline() {
        DispatchQueue.global(qos: .background).async {
            [weak self] in
            guard let strongSelf = self else { return }
            let jsonPath = Bundle.main.path(forResource: "KMLMAPNew", ofType: "json")
            let jsonData = NSData(contentsOfFile: jsonPath!)
            do {
                guard let jsonDict = try JSONSerialization.jsonObject(with: jsonData! as Data, options: []) as? Dictionary<String, AnyObject>, let features = jsonDict["features"] as? Array<AnyObject> else{return}
                for feature in features {
                    guard let feature = feature as? Dictionary<String, AnyObject>, let geometry = feature["geometry"] as? Dictionary<String, AnyObject> else{ continue }
                    if geometry["type"] as? String == "LineString" {
                        var coordinates: [CLLocationCoordinate2D] = []
                        if let locations = geometry["coordinates"] as? Array<AnyObject> {
                            for location in locations {
                                if let location = location as? Array<AnyObject>{
                                    let coordinate = CLLocationCoordinate2DMake(location[1].doubleValue, location[0].doubleValue)
                                    coordinates.append(coordinate)
                                }
                            }
                        }
                        let line = MGLPolyline(coordinates: &coordinates, count: UInt(coordinates.count))
                        line.title = "Crema to Council Crest"
                        print(feature) // Added this line just for debug to see the flow..
                        DispatchQueue.main.async {
                            strongSelf.mapboxView.addAnnotation(line)
                        }
                    }
                }
            }
            catch
            {
                print("GeoJSON parsing failed")
            }
        }
    }

func newWay(){
        DispatchQueue.global(qos: .background).async {
            [weak self] in
            guard let strongSelf = self else { return }
            let jsonPath = Bundle.main.path(forResource: "KMLMAPNew", ofType: "json")
            let jsonData = NSData(contentsOfFile: jsonPath!)
            do {
                if let jsonDict = try JSONSerialization.jsonObject(with: jsonData! as Data, options: []) as? Dictionary<String, AnyObject> {
                    if let features = jsonDict["features"] as? Array<AnyObject> {
                        let chunks = stride(from: 0, to: features.count, by: 2).map {
                            Array(features[$0..<min($0 + 2, features.count)])
                        }
                        for obj in chunks{
                            strongSelf.drawSmallListObj(list: obj as! [Dictionary<String, AnyObject>])
                        }
                    }
                }
            }
            catch
            {
                print("GeoJSON parsing failed")
            }
        }
    }

func drawSmallListObj(list: [Dictionary<String, AnyObject>]){
        for obj in list{
            if let feature = obj as? Dictionary<String, AnyObject> {
                if let geometry = feature["geometry"] as? Dictionary<String, AnyObject> {
                    if geometry["type"] as? String == "LineString" {
                        var coordinates: [CLLocationCoordinate2D] = []
                        if let locations = geometry["coordinates"] as? Array<AnyObject> {
                            for location in locations {
                                if let location = location as? Array<AnyObject>{
                                    let coordinate = CLLocationCoordinate2DMake(location[1].doubleValue, location[0].doubleValue)
                                    coordinates.append(coordinate)
                                }
                            }
                        }
                        let line = MGLPolyline(coordinates: &coordinates, count: UInt(coordinates.count))
                        line.title = "Crema to Council Crest"
                        DispatchQueue.main.async {
                            [weak self] in
                            guard let strongSelf = self else { return }
                            strongSelf.mapboxView.addAnnotation(line)
                        }
                    }
                }
            }
        }
    }

Answer 4

第一个解决方案

可能是你的for循环正在无限时间运行，每次使用高内存时都会将内存分配给nil值的数组，因此会出现此错误。

请通过打印来检查for循环。

第二个解决方案

在didReceiveMemoryWarning

中添加此内容

NSURLCache.sharedURLCache().removeAllCachedResponses()
NSURLCache.sharedURLCache().diskCapacity = 0
NSURLCache.sharedURLCache().memoryCapacity = 0

You can also change the cache policy of the NSURLRequest

let day_url = NSURL(string: "http://www.domain.com")
let day_url_request = NSURLRequest(URL: day_url,
    cachePolicy: NSURLRequestCachePolicy.ReloadIgnoringLocalAndRemoteCacheData,
    timeoutInterval: 10.0)

let day_webView = UIWebView()
day_webView.loadRequest(day_url_request)

有关缓存策略的更多信息here。

Answer 5

在callout上制作你的东西这意味着只有在点击引脚时才执行polyne func mapView（_ mapView：MKMapView，didSelect view：MKAnnotationView）

Answer 6

将分享我在这个奇怪问题上的经验。

对我来说，应用程序崩溃并显示“来自调试器的消息：由于内存问题而终止”，并且仪器并没有太大帮助。记忆-也处于绿色极限之内。所以我不确定是什么原因造成的。而且不可能进行调试，并且无法解决单个设备的问题。

只需重新启动iPhone 6 -问题就暂时消失了。

Answer 7

我收到此错误并感到非常困惑，因为我的应用程序的内存使用量相当小。

最后发现是因为我加载了一些文件作为映射内存，例如：

let data = try Data(contentsOf: url, options: .mappedIfSafe)

我不知道为什么会出现这些奇怪的崩溃，但通常只是加载数据就可以防止崩溃的发生。

来自调试器的消息：由于内存问题而终止

7 个答案: