用数组获取数组，但数组中的数组

Question

我有这样的数据库数据。

["{37.331622, -122.030337}","{37.331593, -122.03051}","{37.331554, -122.030681}","{37.331383, -122.030757}","{37.33108, -122.030772}","{37.330798, -122.030729}","{37.330636, -122.030636}"]

然后，我尝试通过以下代码从数据库中查询数据。

- (void)updateLocations {
    CGFloat kilometers = self.radius/1000.0f;
    //PFUser *user = [PFUser currentUser];
    PFQuery *query = [PFQuery queryWithClassName:@"Session"];
    [query whereKey:@"objectId" equalTo:@"t2udAri048"];
    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
        if (!error) {
            NSLog(@"objects %@",objects);
            NSLog(@"path %@",[objects valueForKey:@"Path"]);
            NSArray *pointsArray = [objects valueForKey:@"Path"];;
            NSInteger pointsCount = pointsArray.count;
            CLLocationCoordinate2D pointsToUse[pointsCount];

            for(int i = 0; i < pointsCount; i++) {
                CGPoint p = CGPointFromString(pointsArray[i]);
                pointsToUse[i] = CLLocationCoordinate2DMake(p.x,p.y);
            }

            MKPolyline *myPolyline = [MKPolyline polylineWithCoordinates:pointsToUse count:pointsCount];
            [self.mapView addOverlay:myPolyline];
            //NSLog(@"Drawed %@",pointsArray);
        }
    }];
}

我得到对象的值-值- objects：@“Path”

( "{37.331622，-122.030337}"，"{37.331593，-122.03051}"，"{37.331554，-122.030681}"，"{37.331383，-122.030757}"，"{37.33108，-122.030772}"，“{37.33108，-122.030729}"，"{37.330636，-122.030636}“)

但我希望

( "{37.331622，-122.030337}"，"{37.331593，-122.03051}"，"{37.331554，-122.030681}"，"{37.331383，-122.030757}"，"{37.33108，-122.030772}"，“{37.33108，-122.030729}"，"{37.330636，-122.030636}“)

我该怎么办？

Answer 1

看起来，objects是一个由一个元素组成的数组，它是一个具有"Path“属性的对象。在这种情况下，您应该替换

NSArray *pointsArray = [objects valueForKey:@"Path"];

通过

NSArray *pointsArray = [objects[0] valueForKey:@"Path"];

Answer 2

在您的示例中，您有了objectId。如果是这样的话，就使用getObjectWithId。这将只返回您想要的对象。

PFQuery *query = PFQuery queryWithClassName:@"Session"；

查询getObjectWithId:@"hr46gjh45"；

您的示例返回一个对象数组；在本例中，数组只有一个对象(但它仍然是一个数组)。在这种情况下，必须首先从数组中检索对象。