当图钉放在地图上时，在注释中显示地址 [英] Show address in annotation when pin is dropped on map
问题描述
目前，我可以在地图上放置图钉.现在，我要注释标题显示放置图钉的地址.
我已经看过这个，但是不能让我上班:
将注释的标题设置为当前地址
ViewController.m中的代码
已更新.
- (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];
}];
}
首先，在addPinToMap:方法中，使用currentLocation调用addressLocation，但从未设置currentLocation.声明了几行，但未设置任何值.
所以改变:
CLLocation *currentLocation;
收件人:
CLLocation *currentLocation = [[CLLocation alloc]
initWithLatitude:touchMapCoordinate.latitude
longitude:touchMapCoordinate.longitude];
第二，即使有了此修复程序，它仍然无法使用.注释的title不会被设置，因为reverseGeocodeLocation方法的完成处理程序块将在添加注释后完成(该块是异步的-addPinToMap:中的代码将不等待其完成). /p>
当您实际获得地址解析器的结果(无论是成功还是失败)时，您需要稍微更改一下代码，并在完成代码块的内部 中添加注释.
将reverseGeocodeLocation调用移至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];
}];
Currently I can drop pins around the map. Now I want the annotation title to display the address of where the pin is dropped.
I've had a look at this but cant get mine to work:
Set annotation's title as current address
Code in my ViewController.m
Updated.
- (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];
}];
}
First, in the addPinToMap: method, addressLocation is called with currentLocation but currentLocation is never set. It's declared a few lines up but not set to any value.
So change:
CLLocation *currentLocation;
to:
CLLocation *currentLocation = [[CLLocation alloc]
initWithLatitude:touchMapCoordinate.latitude
longitude:touchMapCoordinate.longitude];
Second, even with this fix, it still won't work. The annotation's title will not get set because the reverseGeocodeLocation method's completion handler block will finish after the annotation has already been added (the block is asynchronous -- the code in addPinToMap: will not wait for it to finish).
You'll need to change the code around a bit and add the annotation inside the completion block when you actually have the geocoder result (whether success or failure).
Move the reverseGeocodeLocation call to the addPinToMap: method:
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];
}];
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