I'm using MKMapView with many annotations. Everything is OK until i zoom in and zoom out my map. Some annotations' location switch with each others. Anyone know why?
Here are my code that i call after viewDidLoad to import annotations from 3 arrays: longitudes, latitudes and photoFileName.
photoFileName contains photo file names for all annotations, longitudes and latitudes contain coordinates of them.
for (int i=0; i<[longitudes count]; i++)
CLLocation* location = [[CLLocation alloc] initWithLatitude:[latitudes objectAtIndex:i]
longitude:[longitudes objectAtIndex:i]];
CSMapAnnotation* annotation = [[CSMapAnnotation alloc] initWithCoordinate:[location coordinate]
annotationType:CSMapAnnotationTypeImage
title:#"";
subtitle:#"";
// Set data for the annotation. This data is used for displaying annotation
[annotation setUserData:[photoFilename objectAtIndex:i]];
[_mapView addAnnotation:annotation];
[annotation release];
[currentLocation release];
}
Everything loaded OK, scrolling and zooming worked. However, when I zoom in mapview (about 5-10 times bigger), and after that, zoom out again to the first size, some annotations locations are changed (See the bottom annotation).
I don't post the function viewForAnnotation here because it's not called, i just zoom in/out and it happends.
http://cC8.upanh.com/27.800.35078007.mF80/1.png http://cC9.upanh.com/27.800.35078008.AWG0/2.png
Oh, you are right. I solved problem after see again viewForAnnotation function. In my old code, when calling [mapView dequeueReusableAnnotationViewWithIdentifier:identifier], i just set identifier to "Image" for all annotations. It makes this function get a random annotation each time. Solved by specifying the true identifier for each annotation. Thanks for your warning!
Related
Ive got an app that plots mkannotations (i hope i get my terminology right...its kinda confusing) on a mapview.
I have already included the subtitle for when you tap on them.
I have been looking online for a way to include the distance in those callouts but im not quite there yet. I ran across two partial solutions and Im wondering if they should be combined.
First, I didnt have CoreLocation added to my project, I need it right? To be constantly updating my user location and be able to calculate the distances to each point? Or does Mapkit somehow include a user location data that I can use?
Partial Solution A uses this code:
`-(void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation {
if(!newLocation) return;
if ((oldLocation.coordinate.latitude != newLocation.coordinate.latitude) &&
(oldLocation.coordinate.longitude != newLocation.coordinate.longitude)){
CLLocation *loc1 = [[CLLocation alloc] initWithLatitude:oldLocation.coordinate.latitude longitude:oldLocation.coordinate.longitude];
CLLocation *loc2 = [[CLLocation alloc] initWithLatitude:newLocation.coordinate.latitude longitude:newLocation.coordinate.longitude];
CLLocationDistance distance = ([loc2 distanceFromLocation:loc1]) * 0.000621371192;
//distance = distance;
NSLog(#"Total Distance %f in miles",distance);
}
}
I understand this method calculates the distance between 2 points. I would somehow need to cycle thru my annotations and create the distance. It seems this would be the more useful one since it constantly recalculates the distances based on the current userLocation. Although, I do wonder about the effectiveness of that. Once you know how far away something is, you rarely wish to be constantly reminded as to how far away it is.
Partial Solution B uses this code:
`- (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view calloutAccessoryControlTapped:(UIControl *)control{
CLLocation *pinLocation = [[[CLLocation alloc] initWithLatitude:[(MyAnnotation*)[view annotation] coordinate].latitude longitude:[(MyAnnotation*)[view annotation] coordinate].longitude]];
CLLocation *userLocation = [[CLLocation alloc] initWithLatitude:self._mapView.userLocation.coordinate.latitude longitude:self._mapView.userLocation.coordinate.longitude];
CLLocationDistance distance = [pinLocation distanceFromLocation:userLocation];
NSLog(#"Distance to pin %4.0f", distance);
}
`
In this case, whenever the pin is tapped, the distance is calculated. But Im unclear as to the code for MyAnnotation [view annotation], Im guessing the original poster had his locations based off of a MyAnnotation Class so I changed it to MyLocation and all but 1 error went away. I get an Expected Identifier error at the pinLocation line at the last square bracket for some reason.
I feel the solution is in the tip of my tongue. Just need that little extra push :)
Thanks guys
Just move the code inside the calloutAccessoryControlTapped method right after the line, wherever you have it, that creates the MKAnnotation. Give MKAnnotation subclass a float distance property and set it as the subtitle.
I need to display a MKMapView with more than 4 locations with different Annotations and a route connecting the locations. I have tried to display the multiple locations inside a MKMapView but i still not able to find out on how to connect the locations with a route. I am also trying to get this checked if i have implemented it in a right way. I have created a "CLLocationCoordinate2D" and then added a lat and long similarly for 4 points. I have created a custom object which implements MKAnnotation and returning a location .
CLLocationCoordinate2D coordinate1 = CLLocationCoordinate2DMake(40.7180583 ,-74.007109);
CLLocationCoordinate2D coordinate2 = CLLocationCoordinate2DMake(40.716355 ,-74.006816);
CLLocationCoordinate2D coordinate3 = CLLocationCoordinate2DMake(40.715281 ,-74.005485);
CLLocationCoordinate2D coordinate4 = CLLocationCoordinate2DMake(40.71559 ,-74.003114);
AnnotationPoints *location1 = [[AnnotationPoints alloc] initWithCoordinate:coordinate1];
AnnotationPoints *location2 = [[AnnotationPoints alloc] initWithCoordinate:coordinate2];
AnnotationPoints *location3 = [[AnnotationPoints alloc] initWithCoordinate:coordinate3];
AnnotationPoints *location4 = [[AnnotationPoints alloc] initWithCoordinate:coordinate4];
NSArray *poiArray = [[NSArray alloc] initWithObjects:location1,location2,location3,location4,nil];
[mapView addAnnotations:poiArray];
//Inside the Annotation Class initWithCoordinate Method is implemented this way:-
-(id)initWithCoordinate:(CLLocationCoordinate2D) c{
coordinate=c;
NSLog(#"%f,%f",c.latitude,c.longitude);
return self;
}
My concern here is i need to create a Annotation Point for every Location. Is there any alternative that i can load all the points at a single place. And another difficulty here is the route connecting all the multiple points. Any help on this? Thanks a lot
The way you are adding the annotations is fine.
Not sure what your concern is and what you mean by "all the points at a single place".
If you want pins/annotations at several places, you have to create a separate annotation object for each place.
Drawing a route connecting those locations requires creating an overlay (not an "annotation").
You want to add an MKPolyline to the map for which you will specify the list of coordinates.
To draw the polyline, you don't need to also add annotations at each coordinate (but you could if you want to).
Creating and adding an MKPolyline and its corresponding MKPolylineView is very similar to MKPolygon and MKPolygonView. See this question for an example:
iPhone MKMapView - MKPolygon Issues
I make annotations from a response JSON from a Web service.
I can load the pins in the map, but when I move the position of the center I have to reload a new bunch of annotations and delete the old ones. When I do the method it only charges the pins and if I move the center it does the same and recharge.
I've tried a lot of methods like this one...
for (id<MKAnnotation> annotation in _mapView.annotations) {
[_mapView removeAnnotation:annotation];
}
But it only, does this: I gets to the center of the map and when I move the map it returns to the start and I can't zoom the map cause it reloads and loops.
To remove all annotations, just run this before you add the new ones..
NSMutableArray *toRemove = [NSMutableArray arrayWithCapacity:15];
for (id annotation in mapView.annotations){
if (annotation != mapView.userLocation)
[toRemove addObject:annotation];
[mapView removeAnnotations:toRemove];
I have a map view with annotations, and these annotations display a callout. When the callout's disclosure detail button is clicked, it segues into a new view.
My MKAnnotations are a custom class that implements <MKAnnotation>. Let's call that class MyClass. They are stored in an NSMutableArray. During viewdidload of this view, I add each object of MyClass in this array to the map view's annotations. Using the debugger, I can see that once all of this adding is done, the [self.MapView annotations] order is the same as the NSMutableArray.
Now I set another breakpoint within mapView:viewForAnnotation: and check out the order of 1) my NSMutableArray and 2) [self.MapView annotations]. The array is of course in the same order. However, the order of the annotations has been scrambled.
This was a big problem for me, because I needed to use the specific instance of MyClass that the user selected in the next view. AKA, I wanted to look at the annotation, find its index, and then use that to get the same index within the array.
I've now realized that I can just save the annotation directly (coming from an Android background, this was very cool to me). However, I am still conceptually at a loss as to why the order became scrambled. Can someone help me? Code below:
- (void)viewDidLoad
{
if([fromString isEqualToString:#"FromList"])
self.navigationItem.hidesBackButton = TRUE;
else {
self.navigationItem.rightBarButtonItem = nil;
}
self.array = [MySingleton getArray];
//set up map
//declare latitude and longitude of map center
CLLocationCoordinate2D center;
center.latitude = 45;
center.longitude = 45;
//declare span of map (height and width in degrees)
MKCoordinateSpan span;
span.latitudeDelta = .4;
span.longitudeDelta = .4;
//add center and span to a region,
//adjust the region to fit in the mapview
//and assign to mapview region
MKCoordinateRegion region;
region.center = center;
region.span = span;
MapView.region = [MapView regionThatFits:region];
for(MyClass *t in self.array){
[MapView addAnnotation:t];
}
[super viewDidLoad];
}
//this is the required method implementation for MKMapView annotations
- (MKAnnotationView *) mapView:(MKMapView *)thisMapView
viewForAnnotation:(MyClass *)annotation
{
static NSString *identifier = #"MyIdentifier";
//the result of the call is being cast (MKPinAnnotationView *) to the correct
//view class or else the compiler complains
MKPinAnnotationView *annotationView = (MKPinAnnotationView *)[thisMapView
dequeueReusableAnnotationViewWithIdentifier:identifier];
if(annotationView == nil)
{
annotationView = [[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:identifier];
}
annotationView.pinColor = MKPinAnnotationColorGreen;
//pin drops when it first appears
annotationView.animatesDrop=TRUE;
//tapping the pin produces a gray box which shows title and subtitle
annotationView.canShowCallout = YES;
UIButton *infoButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
annotationView.rightCalloutAccessoryView = infoButton;
return annotationView;
}
When you call addAnnotation or addAnnotations, the map view adds the reference(s) to its internal list of annotations.
The annotations property of MKMapView simply returns this internal list (whatever type it might be) as an NSArray.
I don't know of any place in the documentation where it states that the annotations property returns the array in the same order that you added the annotations in. If you have showsUserLocation turned on, the array will include that annotation even though you didn't explicitly add it.
You do not need to be concerned about nor should you depend on the order of the objects in the annotations property.
Just a few suggestions regarding the code:
Since your array contains objects that implement <MKAnnotation>, instead of looping through it, you can add all the annotations in one shot by calling addAnnotations (plural) and pass it the array
In viewForAnnotation, none of the properties you are setting depend on any specific annotation so you can set them all inside the if (av == nil) block. This way you get maximum reuse.
Also in viewForAnnotation, after and outside the if, you should set the annotation property of the view to the current annotation. This is in case the view is being reused from another annotation.
Finally, in viewForAnnotation, don't assume the annotation will be of type MyClass. If you turn on showsUserLocation, that won't be the case. It's safer to declare the parameter as id<MKAnnotation> and then if necessary check what its class is and then cast it.
#Anna, you state you should not be concerned for the order of the annotations. That's not true in my case. Some annotationviews might overlap, and I always need a specific one to be on the top of the two overlapping views. So the order DO makes sense for the annotations, as I hope the - (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation gets called in the same order as i added the annotations.
EDIT:
and the solution is here :-)
In my application I have a MKMapView where several annotations are shown. The map rotates based on the heading of the device. To rotate the map the following statement is performed (called by the method locationManager: didUpdateHeading:)
self.navigationMapView.mapView.transform = CGAffineTransformMakeRotation(-heading);
where the heading (magnetic) is expressed in radians. What I noticed it's that even the annotations in the map rotate and I don't want it. I tried to fix it in the following method:
- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation{
static NSString *identifier = #"AnnotationViewIdentifier";
MKAnnotationView *av = [mapView dequeueReusableAnnotationViewWithIdentifier:identifier];
if (av == nil) {
av = [[[MKPinAnnotationView alloc]initWithAnnotation:annotation reuseIdentifier:identifier] autorelease];
}
else{
av.annotation = annotation;
}
av.transform = CGAffineTransformMakeRotation(degreesToRadians(self.arController.currentHeading.magneticHeading));
av.canShowCallout = YES;
return av;
}
and I want to call this method from "didUpdateHeading:" but I really don't know how to do it. The TableView class has the reloadData function that calls the delegate method but here the things seem different. Any suggestions?!
Another question, my annotations on the map show the distance from the user, I would like to update them (distance label) as soon as the user change location. Any suggestions?!
So with a MKMapView having that be called properly is a little bit annoying. Essentially you have one of two options. Option 1: Create an array of the annotation on the screen and remove that from the map_view and then re-add them to the map_view. Essentially creating your own reload data function. Option 2: Do something simple such as
CGLocationCoordinate2D coordinate = map_view.center;
map_view.center = coordinate;
-- Essentially the point is to reset a property of the map causing it to redraw. However this option is not always going to work. Option 1 has a higher chance of working however that one can also fail, so if simply taking the annotations off and re-adding them causes nothing to happen then simply decreate the map and then recreate the map at the end of your map refresh function something like.
[my_map_view removeFromSuperView];
[my_map_view release];
my_map_view = nil;
my_map_view = [[MKMapView alloc] initWithFrame:CGRectMake(0,0,320,480)];
one of these options should work. I had to do option one for my solution however I know some people are lucky and option 2 works just as well.