在地图上放置图钉时在注释中显示地址

Question

目前我可以在地图上放置图钉。 现在，我希望注释标题显示引脚放置位置的地址。

我已经看过这个，但无法让我的工作：
将批注的标题设置为当前地址

我的视图控制器中的代码.m

更新。

- (void)addPinToMap:(UIGestureRecognizer *)gestureRecognizer
{
    if (gestureRecognizer.state != UIGestureRecognizerStateBegan)
        return;
    CGPoint touchPoint = [gestureRecognizer locationInView:self.map];
    CLLocationCoordinate2D touchMapCoordinate =
    [self.map convertPoint:touchPoint toCoordinateFromView:self.map];
    CLLocation *currentLocation = [[CLLocation alloc]
                                   initWithLatitude:touchMapCoordinate.latitude
                                   longitude:touchMapCoordinate.longitude];
    [self.geocoder reverseGeocodeLocation:currentLocation completionHandler:^(NSArray *placemark, NSError *error) {
        //initialize the title to "unknown" in case geocode has failed...
        NSString *annTitle = @"Address unknown";
        //set the title if we got any placemarks...
        if (placemark.count > 0)
        {
            CLPlacemark *topResult = [placemark objectAtIndex:0];
            annTitle = [NSString stringWithFormat:@"%@ %@ %@ %@", topResult.country, topResult.locality, topResult.subLocality, topResult.thoroughfare];
        }
        //now create the annotation...
        MapAnnotation *toAdd = [[MapAnnotation alloc]init];
        toAdd.coordinate = touchMapCoordinate;
        toAdd.title = annTitle;
        //toAdd.title = @"Title";
        toAdd.subtitle = @"Subtitle";
        [self.map addAnnotation:toAdd];
    }];
}

Answer 1

首先，在 addPinToMap: 方法中，使用 currentLocation 调用addressLocation，但从未设置currentLocation。 它声明了几行，但未设置为任何值。

所以改变：

CLLocation *currentLocation;

自：

CLLocation *currentLocation = [[CLLocation alloc] 
                                initWithLatitude:touchMapCoordinate.latitude 
                                longitude:touchMapCoordinate.longitude];

其次，即使有此修复程序，它仍然不起作用。 不会设置注释的title，因为reverseGeocodeLocation方法的完成处理程序块将在添加注释后完成（块是异步的 - addPinToMap:中的代码不会等待它完成）。

当您

实际获得地理编码器结果（无论是成功还是失败）时，您需要稍微更改代码并在完成块中添加注记。

将reverseGeocodeLocation调用移动到addPinToMap:方法：

CLLocation *currentLocation = [[CLLocation alloc] 
                                initWithLatitude:touchMapCoordinate.latitude 
                                longitude:touchMapCoordinate.longitude];
[self.geocoder reverseGeocodeLocation:currentLocation completionHandler:^(NSArray *placemark, NSError *error) {
    //initialize the title to "unknown" in case geocode has failed...
    NSString *annTitle = @"Address unknown";
    //set the title if we got any placemarks...
    if (placemark.count > 0)
    {
        CLPlacemark *topResult = [placemark objectAtIndex:0];
        annTitle = [NSString stringWithFormat:@"%@ %@ %@ %@", topResult.country, topResult.locality, topResult.subLocality, topResult.thoroughfare];
    }
    //now create the annotation...
    MapAnnotation *toAdd = [[MapAnnotation alloc]init];
    toAdd.coordinate = touchMapCoordinate;
    toAdd.title = annTitle;
    toAdd.subtitle = @"Subtitle";
    [self.map addAnnotation:toAdd];
}];