如何从视图控制器访问内存中的自定义对象？ [英] How do I access a custom object in memory from a view controller?

问题描述

在我的应用程序中，我获取一个核心数据库并将结果放入一个名为self.stores的数组中。我将这些存储位置转换为具有distance属性的MyLocation对象。我这样绘制MyLocation对象：

In my app I fetch a coredatabase and put results into an array called self.stores. I convert those store locations to MyLocation objects which have a distance property. I plot the MyLocation objects like so:

- (void)plotStorePositions:(NSString *)responseString {

    for (id<MKAnnotation> annotation in _mapView.annotations) {
        [_mapView removeAnnotation:annotation];
    }
    //CYCLE THRU STORE OBJECTS
    for (Store * storeObject in self.stores) {

        NSString * latitude = storeObject.latitude;
        NSString * longitude = storeObject.longitude;
        NSString * storeDescription = storeObject.name;
        NSString * address = storeObject.address;

        //CREATE MYLOCATION OBJECTS
        CLLocationCoordinate2D coordinate;
        coordinate.latitude = latitude.doubleValue;
        coordinate.longitude = longitude.doubleValue;
        MyLocation *annotation = [[MyLocation alloc] initWithName:storeDescription address:address coordinate:coordinate distance:0];

        //CREATE A PIN FOR EACH MYLOCATION ANNOTATION
        CLLocation *pinLocation = [[CLLocation alloc] initWithLatitude:annotation.coordinate.latitude longitude:annotation.coordinate.longitude];

        //SET USERLOCATION (Must move this code out)
        self.userLocation = [[CLLocation alloc] initWithLatitude:self._mapView.userLocation.coordinate.latitude longitude:self._mapView.userLocation.coordinate.longitude];

        //SET USERLOCATION TO APPDELEGATE (Must move this code out)
        AppDelegate *myDelegate = [[UIApplication sharedApplication] delegate];
        myDelegate.userLocation = self.userLocation;

        //CALCULATE DISTANCE AND SET ITS THAT MYLOCATION's DISTANCE PROPERTY
        CLLocationDistance calculatedDistance = [pinLocation distanceFromLocation:userLocation];
        annotation.distance = calculatedDistance/1000;        

        [_mapView addAnnotation:annotation];

    }

}

这是在地图视图。然后，我有一个表视图，在这里我提取相同的coredatabase并再次获取self.stores。然后，我循环遍历self.stores的数组以创建STORE storeObjects并将其放入我的tableview单元格中。但是我想对那些单元格进行排序。如何获取应该在内存中的MyLocation对象？我需要将它们传递给appDelegate还是tableview控制器？

This is in a mapview. I then have a tableview where I fetch the same coredatabase and get self.stores again. Then I cycle through that array of self.stores to create STORE storeObjects to put into my tableview cells. But I want to sort those cells. How do I get MyLocation objects which should be in memory? Do I need to pass them to the appDelegate or to the tableview controller?

推荐答案

在使用Core Data时，最好的选择是是使用 NSFetchedResultsController 填充表格视图。

As you are using Core Data, your best option is to use a NSFetchedResultsController to populate your table view.

然后，您需要的只是来自另一个控制器或应用程序委托的托管对象上下文。

All you need then is the managed object context, either from another controller or the app delegate.

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