objective-c - MKMapView 不刷新注释

Question

我有一个 MKMapView(显然)，它显示了用户周围的住房位置。

我有一个半径工具，当进行选择时，注释应该根据用户周围的距离添加/删除。

我可以很好地添加/删除它，但由于某种原因，注释在我放大或缩小之前不会显示。

这是基于距离添加/删除注释的方法。我尝试了该方法的两种不同变体。

将新注释添加到数组中，然后通过 [mapView addAnnotations:NSArray] 添加到 map 中.

使用 [mapView addAnnotation:MKMapAnnotation] 添加找到的注释;

1.

- (void)updateBasedDistance:(NSNumber *)distance {

    //Setup increment for HUD animation loading
    float hudIncrement = ( 1.0f / [[[[self appDelegate] rssParser]rssItems] count]);

    //Remove all the current annotations from the map
    [self._mapView removeAnnotations:self._mapView.annotations];

    //Hold all the new annotations to add to map
    NSMutableArray *tempAnnotations;

    /* 
     I have an array that holds all the annotations on the map becuase 
     a lot of filtering/searching happens. So for memory reasons it is
     more efficient to load annoations once then add/remove as needed.
    */
    for (int i = 0; i < [annotations count]; i++) {

        //Current annotations location
        CLLocation *tempLoc = [[CLLocation alloc] initWithLatitude:[[annotations objectAtIndex:i] coordinate].latitude longitude:[[annotations objectAtIndex:i] coordinate].longitude];

        //Distance of current annotaiton from user location converted to miles
        CLLocationDistance miles = [self._mapView.userLocation.location distanceFromLocation:tempLoc] * 0.000621371192;

        //If distance is less than user selection, add it to the map. 
        if (miles <= [distance floatValue]){
            if (tempAnnotations == nil)
                tempAnnotations = [[NSMutableArray alloc] init];
            [tempAnnotations addObject:[annotations objectAtIndex:i]];
        }

        //For some reason, even with ARC, helps a little with memory consumption
        tempLoc = nil;

        //Update a progress HUD I use. 
        HUD.progress += hudIncrement;
    }

    //Add the new annotaitons to the map
    if (tempAnnotations != nil)
        [self._mapView addAnnotations:tempAnnotations];
}

2.

- (void)updateBasedDistance:(NSNumber *)distance {

    //Setup increment for HUD animation loading
    float hudIncrement = ( 1.0f / [[[[self appDelegate] rssParser]rssItems] count]);

    //Remove all the current annotations from the map
    [self._mapView removeAnnotations:self._mapView.annotations];

    /* 
     I have an array that holds all the annotations on the map becuase 
     a lot of filtering/searching happens. So for memory reasons it is
     more efficient to load annoations once then add/remove as needed.
    */
    for (int i = 0; i < [annotations count]; i++) {

        //Current annotations location
        CLLocation *tempLoc = [[CLLocation alloc] initWithLatitude:[[annotations objectAtIndex:i] coordinate].latitude longitude:[[annotations objectAtIndex:i] coordinate].longitude];

        //Distance of current annotaiton from user location converted to miles
        CLLocationDistance miles = [self._mapView.userLocation.location distanceFromLocation:tempLoc] * 0.000621371192;

        //If distance is less than user selection, add it to the map. 
        if (miles <= [distance floatValue])
            [self._mapView addAnnotation:[annotations objectAtIndex:i]];

        //For some reason, even with ARC, helps a little with memory consumption
        tempLoc = nil;

        //Update a progress HUD I use. 
        HUD.progress += hudIncrement;
    }
}

在上述方法结束时我也尝试过:

[self._mapView setNeedsDisplay];
[self._mapView setNeedsLayout];

另外，要强制刷新(在某个地方看到它可能会起作用):

self._mapView.showsUserLocation = NO;
self._mapView.showsUserLocation = YES;

任何帮助将不胜感激，并一如既往地感谢您抽出宝贵的时间阅读。

Answer 1

我猜updateBasedDistance:从后台线程调用。联系 NSLog(@"Am I in the UI thread? %d", [NSThread isMainThread]); .如果是 0 , 那么你应该移动 removeAnnotations:和 addAnnotation:到 performSelectorOnMainThread:调用，或者在主线程上使用 GCD block 。