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我的应用程序加载用户过去的折线并将它们显示在地图上。然后应用程序开始跟踪，并从最后更新的坐标到第一个坐标绘制一条直线，从而在两条单独的线应该分开时将它们连接起来（如图所示）

我想删除这条直线，所以我认为最简单的方法是丢弃超出设定时间范围（例如 1 分钟）的坐标，因此地图上的折线保持独立。我不知道该怎么做……我是初学者，所以任何建议都将不胜感激！

我在加载过去的折线时使用此代码

(IBAction)didClickLoadCoordinates:(id)sender {
// get a reference to the appDelegate so you can access the global managedObjectContext
AppDelegate *appDelegate = [UIApplication sharedApplication].delegate;

NSFetchRequest *request = [[NSFetchRequest alloc] initWithEntityName:@"Route"];
NSError *error;
id results = [appDelegate.managedObjectContext executeFetchRequest:request error:&error];

if ([results count]) {
    polyLine = (Route *)(results[0]);
    NSArray *coordinates = polyLine.coordinates;
    int ct = 0;
    for (CLLocation *loc in coordinates) {
        NSLog(@"location %d: %@", ct++, loc);
    }


    // this copies the array to your mutableArray
    _locationsArray = [coordinates mutableCopy];

}

NSInteger numberOfSteps = _locationsArray.count;

//convert to coordinates array to construct the polyline

CLLocationCoordinate2D clCoordinates[numberOfSteps];
for (NSInteger index = 0; index < numberOfSteps; index++) {
    CLLocation *location = [_locationsArray objectAtIndex:index];
    CLLocationCoordinate2D coordinate2 = location.coordinate;
    clCoordinates[index] = coordinate2;
}

MKPolyline *routeLine = [MKPolyline polylineWithCoordinates:clCoordinates count:numberOfSteps];
[_mapView addOverlay:routeLine];

- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations{

这段代码通常会更新 cllocations 并制作折线

//get the latest location
CLLocation *currentLocation = [locations lastObject];


//get latest location coordinates
CLLocationDegrees latitude = currentLocation.coordinate.latitude;
CLLocationDegrees longitude = currentLocation.coordinate.longitude;
CLLocationCoordinate2D locationCoordinates = CLLocationCoordinate2DMake(latitude, longitude);

//zoom map to show users location
MKCoordinateRegion viewRegion = MKCoordinateRegionMakeWithDistance(locationCoordinates, 2000, 2000);
MKCoordinateRegion adjustedRegion = [_mapView regionThatFits:viewRegion];
[_mapView setRegion:adjustedRegion animated:YES];


    //store latest location in stored track array
    [_locationsArray addObject:currentLocation];


//create cllocationcoordinates to use for construction of polyline
NSInteger numberOfSteps = _locationsArray.count;
CLLocationCoordinate2D coordinates[numberOfSteps];
for (NSInteger index = 0; index < numberOfSteps; index++) {
    CLLocation *location = [_locationsArray objectAtIndex:index];
    CLLocationCoordinate2D coordinate2 = location.coordinate;
    coordinates[index] = coordinate2;
}

MKPolyline *routeLine = [MKPolyline polylineWithCoordinates:coordinates count:numberOfSteps];
[_mapView addOverlay:routeLine];

NSLog(@"%@", _locationsArray);
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