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我是 iOS 新手，正在研究谷歌地图。

我想根据键值将我的旅行路线图（带折线）保存到我的核心数据中。

使用 till 进行保存的代码（来自 runkeeper 应用程序）

- (void)saveRun
{
Run *newRun = [NSEntityDescription insertNewObjectForEntityForName:@"Run"
                                            inManagedObjectContext:self.managedObjectContext];

newRun.distance = [NSNumber numberWithFloat:self.distance];
newRun.duration = [NSNumber numberWithInt:self.seconds];
newRun.timestamp = [NSDate date];

NSMutableArray *locationArray = [NSMutableArray array];
for (CLLocation *location in self.locations) {
    Location *locationObject = [NSEntityDescription insertNewObjectForEntityForName:@"Location"
                                                             inManagedObjectContext:self.managedObjectContext];

    locationObject.timestamp = location.timestamp;
    locationObject.latitude = [NSNumber numberWithDouble:location.coordinate.latitude];
    locationObject.longitude = [NSNumber numberWithDouble:location.coordinate.longitude];
    [locationArray addObject:locationObject];
}

newRun.locations = [NSOrderedSet orderedSetWithArray:locationArray];
self.run = newRun;

// Save the context.
NSError *error = nil;
if (![self.managedObjectContext save:&error]) {
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    abort();
  }
}

然后在我想根据键值获取折线详细信息并显示在 MapView 上之后。

用于获取

- (MKCoordinateRegion)mapRegion
{
  MKCoordinateRegion region;
  Location *initialLoc = self.run.locations.firstObject;

float minLat = initialLoc.latitude.floatValue;
float minLng = initialLoc.longitude.floatValue;
float maxLat = initialLoc.latitude.floatValue;
float maxLng = initialLoc.longitude.floatValue;

for (Location *location in self.run.locations) {
    if (location.latitude.floatValue < minLat) {
        minLat = location.latitude.floatValue;
    }
    if (location.longitude.floatValue < minLng) {
        minLng = location.longitude.floatValue;
    }
    if (location.latitude.floatValue > maxLat) {
        maxLat = location.latitude.floatValue;
    }
    if (location.longitude.floatValue > maxLng) {
        maxLng = location.longitude.floatValue;
    }
}

region.center.latitude = (minLat + maxLat) / 2.0f;
region.center.longitude = (minLng + maxLng) / 2.0f;

region.span.latitudeDelta = (maxLat - minLat) * 1.1f; // 10% padding
region.span.longitudeDelta = (maxLng - minLng) * 1.1f; // 10% padding

return region;
}

- (MKPolyline *)polyLine {

CLLocationCoordinate2D coords[self.run.locations.count];

for (int i = 0; i < self.run.locations.count; i++) {
    Location *location = [self.run.locations objectAtIndex:i];
    coords[i] = CLLocationCoordinate2DMake(location.latitude.doubleValue,location.longitude.doubleValue);
}

return [MKPolyline polylineWithCoordinates:coords count:self.run.locations.count];
}
- (void)loadMap
{
if (self.run.locations.count > 0) {

    self.mapView.hidden = NO;

    // set the map bounds
    [self.mapView setRegion:[self mapRegion]];

    // make the line(s!) on the map
    NSArray *colorSegmentArray = [MathController colorSegmentsForLocations:self.run.locations.array];
   [self.mapView addOverlays:colorSegmentArray];
    //[self.mapView addOverlay:[self polyLine]];
    [self.mapView addAnnotations:[[BadgeController defaultController] annotationsForRun:self.run]];
} else {

    // no locations were found!
    self.mapView.hidden = YES;

    UIAlertView *alertView = [[UIAlertView alloc]
                              initWithTitle:@"Error"
                              message:@"Sorry, this run has no locations saved."
                              delegate:nil
                              cancelButtonTitle:@"OK"
                              otherButtonTitles:nil];
    [alertView show];
}
}

主要是使用键值保存路径并仅使用该键值获取。

任何人都可以帮助我。

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