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Radius工具，当选择时，应根据用户周围的距离添加/删除注释。

我添加/删除很好，但由于某种原因，注释在我放大或缩小之前不会显示。

这是根据距离添加/删除注释的方法。我尝试了两种不同的方法。

将新注释添加到数组中，然后按[mapView addAnnotations:NSArray]添加到地图。
使用[mapView addAnnotation:MKMapAnnotation];

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;
    }
}

我还尝试了上述方法的结尾：

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

另外，强制刷新（看到它可能起作用的地方）：

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

非常感谢任何帮助，并且一如既往，感谢您抽出宝贵时间阅读。

Answer 1

我猜测从后台线程调用updateBasedDistance:。查看NSLog(@"Am I in the UI thread? %d", [NSThread isMainThread]);。如果是0，那么您应该将removeAnnotations:和addAnnotation:移动到performSelectorOnMainThread:调用，或者使用主线程上的GCD块。

MKMapView没有刷新注释

1 个答案: