I have an app set in San Francisco, which plots points on a map. Once the points are plotted, I use this code to zoom and pan the map to fit all the points:
//BASE_RADIUS = 0.0144927536
- (MKCoordinateRegion)regionFromLocations:(NSArray*)locations {
if([locations count] <= 0) {
MKCoordinateRegion region = self.mapView.region;
return region;
}
CLLocationCoordinate2D upper = [[locations objectAtIndex:0] coordinate];
CLLocationCoordinate2D lower = [[locations objectAtIndex:0] coordinate];
// FIND LIMITS
for(MapPinModel *eachLocation in locations) {
if([eachLocation coordinate].latitude > upper.latitude) upper.latitude = [eachLocation coordinate].latitude;
if([eachLocation coordinate].latitude < lower.latitude) lower.latitude = [eachLocation coordinate].latitude;
if([eachLocation coordinate].longitude > upper.longitude) upper.longitude = [eachLocation coordinate].longitude;
if([eachLocation coordinate].longitude < lower.longitude) lower.longitude = [eachLocation coordinate].longitude;
}
// FIND REGION
MKCoordinateSpan locationSpan;
locationSpan.latitudeDelta = upper.latitude - lower.latitude;
locationSpan.longitudeDelta = upper.longitude - lower.longitude;
if(locationSpan.latitudeDelta < BASE_RADIUS) { locationSpan.latitudeDelta = BASE_RADIUS; }
if(locationSpan.longitudeDelta < BASE_RADIUS) { locationSpan.longitudeDelta = BASE_RADIUS; } //the smallest it gets is a mile.
CLLocationCoordinate2D locationCenter;
locationCenter.latitude = (upper.latitude + lower.latitude) / 2;
locationCenter.longitude = (upper.longitude + lower.longitude) / 2;
MKCoordinateRegion region = MKCoordinateRegionMake(locationCenter, locationSpan);
return region;
}
I then zoom the map to this region using:
MKCoordinateRegion region = [self regionFromLocations:_data];
[mapView setRegion:region animated:YES]; //shows all the pins
This works about 95% of the time. The other five percent, the map zooms to Antarctica. The strange thing is, I've caught the zoom in the debugger once, and the coordinates are inside San Francisco. Any ideas on what may be happening here?
Related
I draw path on MKMapView based on coordinates stored in SQLite on iPhone.
But now I stored 14000 coordinates (just lat/lng) in database and now when I want to display overlay path I get application crash.
My question is is there any way to optimize this code to be faster?
This is in view did load:
// ar is NSMutableArray and it is populate from database for a few seconds but code bellow cost me app crash
for(Path* p in ar)
{
self.routeLine = nil;
self.routeLineView = nil;
// while we create the route points, we will also be calculating the bounding box of our route
// so we can easily zoom in on it.
MKMapPoint northEastPoint;
MKMapPoint southWestPoint;
// create a c array of points.
MKMapPoint* pointArr = malloc(sizeof(CLLocationCoordinate2D) * ar.count);
for(int idx = 0; idx < ar.count; idx++)
{
Path *m_p = [ar objectAtIndex:idx];
CLLocationDegrees latitude = m_p.Latitude;
CLLocationDegrees longitude = m_p.Longitude;
// create our coordinate and add it to the correct spot in the array
CLLocationCoordinate2D coordinate = CLLocationCoordinate2DMake(latitude, longitude);
MKMapPoint point = MKMapPointForCoordinate(coordinate);
// adjust the bounding box
// if it is the first point, just use them, since we have nothing to compare to yet.
if (idx == 0) {
northEastPoint = point;
southWestPoint = point;
}
else
{
if (point.x > northEastPoint.x)
northEastPoint.x = point.x;
if(point.y > northEastPoint.y)
northEastPoint.y = point.y;
if (point.x < southWestPoint.x)
southWestPoint.x = point.x;
if (point.y < southWestPoint.y)
southWestPoint.y = point.y;
}
pointArr[idx] = point;
}
// create the polyline based on the array of points.
self.routeLine = [MKPolyline polylineWithPoints:pointArr count:ar.count];
_routeRect = MKMapRectMake(southWestPoint.x, southWestPoint.y, northEastPoint.x - southWestPoint.x, northEastPoint.y - southWestPoint.y);
// clear the memory allocated earlier for the points
free(pointArr);
[self.mapView removeOverlays: self.mapView.overlays];
// add the overlay to the map
if (nil != self.routeLine) {
[self.mapView addOverlay:self.routeLine];
}
UPDATE
ViewDidLoad:
...
[self performSelectorInBackground:#selector(drawPathInBackground) withObject:nil];
...
-(void)drawPathInBackground{
for(int idx = 0; idx < ar.count; idx++)
{ ... }
[self.mapView performSelector:#selector(addOverlay:) onThread:[NSThread mainThread] withObject:self.routeLine waitUntilDone:YES];
}
I did like this and UI not freezes.
The only thing that left is how to draw MKPolyLine on every X points?
three approaches:
don't display every point but rather combine nearby points to just one. the saving depends on your data and the necessity to display all.
if possible load the data in a background thread and display in multiple batches on the main thread. the user will practically see how the data is loaded after time.
load and display data lazily. means: only display those points which are visible on screen
Do fetching from the database and processing in a background thread.
Then reduce the number of coordinates in the path using the Douglas–Peucker algorithm:
And cache the results.
If you have array of coordinates the use this code
here routes is array of coordinates.
NSLog(#"count %d",[routes count]);
MKMapPoint* pointArr = malloc(sizeof(CLLocationCoordinate2D) * [routes count]);
for(int idx = 0; idx < [routes count]; idx++)
{
CLLocation* location = [routes objectAtIndex:idx];
CLLocationCoordinate2D workingCoordinate;
workingCoordinate.latitude=location.coordinate.latitude;
workingCoordinate.longitude=location.coordinate.longitude;
NSLog(#"loop = %f,%f",workingCoordinate.latitude, workingCoordinate.longitude);
MKMapPoint point = MKMapPointForCoordinate(workingCoordinate);
pointArr[idx] = point;
}
// create the polyline based on the array of points.
self.routeLine = [MKPolyline polylineWithPoints:pointArr count:[routes count]];
[mapView addOverlay:self.routeLine];
free(pointArr);
Hope this helps.
google has a algorithm that can encode the locations to string.
for your situation , 14000 coordinates will be encoded to a String nearly 14000 length.
then put the String into sqlite.
it will accelerate the speed to get data from DB
I have created an application that constantly reads the current user coordinates and store them in a SQLite database.
I have a map that is displayed over the whole screen.
And now I want to draw a line over the map while the user moves.
I already created all this.
The problem is that I can't make it to be a 'live'. The Overlay is not updating.
This is the logic:
In ViewDidLoad I have
...
if (nil != self.routeLine) {
[self.mapView addOverlay:self.routeLine];
}
In a function that handle each new coordinates I have:
...
NSString* coordinate = [NSString stringWithFormat:#"%f,%f", thisLocation.longitude, thisLocation.latitude];
[self.paths addObject:coordinate];
MKMapPoint northEastPoint;
MKMapPoint southWestPoint;
// create a c array of points.
MKMapPoint* pointArr = malloc(sizeof(CLLocationCoordinate2D) * self.paths.count);
for(int idx = 0; idx < self.paths.count; idx++)
{
// break the string down even further to latitude and longitude fields.
NSString* currentPointString = [self.paths objectAtIndex:idx];
NSArray* latLonArr = [currentPointString componentsSeparatedByCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:#","]];
CLLocationDegrees latitude = [[latLonArr objectAtIndex:1] doubleValue];
CLLocationDegrees longitude = [[latLonArr objectAtIndex:0] doubleValue];
// create our coordinate and add it to the correct spot in the array
CLLocationCoordinate2D coordinate = CLLocationCoordinate2DMake(latitude, longitude);
MKMapPoint point = MKMapPointForCoordinate(coordinate);
// adjust the bounding box
// if it is the first point, just use them, since we have nothing to compare to yet.
if (idx == 0) {
northEastPoint = point;
southWestPoint = point;
}
else
{
if (point.x > northEastPoint.x)
northEastPoint.x = point.x;
if(point.y > northEastPoint.y)
northEastPoint.y = point.y;
if (point.x < southWestPoint.x)
southWestPoint.x = point.x;
if (point.y < southWestPoint.y)
southWestPoint.y = point.y;
}
pointArr[idx] = point;
}
// create the polyline based on the array of points.
self.routeLine = [MKPolyline polylineWithPoints:pointArr count:self.paths.count];
_routeRect = MKMapRectMake(southWestPoint.x, southWestPoint.y, northEastPoint.x - southWestPoint.x, northEastPoint.y - southWestPoint.y);
// clear the memory allocated earlier for the points
free(pointArr);
This is viewForOverlay delegate function:
- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay
{
MKOverlayView* overlayView = nil;
if(overlay == self.routeLine)
{
//if we have not yet created an overlay view for this overlay, create it now.
if(nil == self.routeLineView)
{
self.routeLineView = [[MKPolylineView alloc] initWithPolyline:self.routeLine];
self.routeLineView.fillColor = [UIColor blueColor];
self.routeLineView.strokeColor = [UIColor blueColor];
self.routeLineView.lineWidth = 5;
}
overlayView = self.routeLineView;
}
return overlayView;
}
In viewDidLoad, the code calls addOverlay with self.routeLine which I assume is initially set to the previously-saved coordinates.
The map view adds the MKPoyline that routeLine points to into its internal list of overlays and draws the overlay.
Then, in the "function that handles each new coordinate", self.routeLine is changed to point to a new MKPolyline.
The reason the overlay view is not updated by the map is because the map view is still using the original MKPolyline that was passed to it when addOverlay was called.
Since MKPolyline itself is not mutable (it does not allow one to change the list of points/coordinates after creation), there are two main options:
Remove the existing overlay and add a new one with the updated coordinates. This is the simplest option. After setting self.routeLine to a new MKPolyline, do the following (for example):
[self.mapView removeOverlays:mapView.overlays];
self.routeLineView = nil;
[self.mapView addOverlay:self.routeLine];
The main drawback to this simple approach is that the overlay will seem to flicker if the updates are done frequently or if the overlay is large or complex.
The alternative is to create a custom overlay and overlay view that are mutable and enabling you to dynamically refresh the overlay more quickly and smoothly.
Fortunately, Apple has provided a sample app called Breadcrumb which does exactly that.
Maybe you just forgot to call [self.view setNeedsDisplay]?
UIView docs
I have an MKMapView, and I'm trying to set the map, so that when you first load the application it goes to a user set location, and if the user hasn't set one, to a default one. The problem is that it always seems to go to 0 latitude, 0 longitude.
-(void) viewDidLoad {
[worldView setShowsUserLocation:YES];
double longitude = [[NSUserDefaults standardUserDefaults] doubleForKey:WhereamiNewLongPrefKey];
double latitude = [[NSUserDefaults standardUserDefaults] doubleForKey:WhereamiNewLatPrefKey];
CLLocationCoordinate2D savedLoc = CLLocationCoordinate2DMake(latitude, longitude);
MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(savedLoc, 250, 250);
NSLog(#"latitude :%f", region.center.latitude);
NSLog(#"longitude :%f", region.center.longitude);
[worldView setRegion:region animated:YES];
}
I've tried setting setShowUserLocation to NO, but that doesn't work. I know it's reading the correct region, because the NSLog is outputing the default latitude, but the map insists on going to somewhere in China...
I've also tried setting the region in mapView:didUpdateUserLocation:, but still the same result.
What am I doing wrong?
EDIT: I added the NSLog to output the longitude as well. The output is:
2012-11-14 09:50:30.699 Whereami[34256:13d03] latitude :20.516700
2012-11-14 09:50:30.699 Whereami[34256:13d03] longitude :99.900000
CLLocationCoordinate2D theCoordinate;
theCoordinate.latitude = 20.516700;
theCoordinate.longitude = 99.900000;
MKCoordinateRegion viewRegion = MKCoordinateRegionMakeWithDistance(theCoordinate, 1000, 1000);
MKCoordinateRegion adjustedRegion = [self.mapView regionThatFits:viewRegion];
[self.mapView setRegion:adjustedRegion animated:YES];
I am working on MapView,on which I have two buttons.
1)centreButton:
this button drops the pin annotation at the centre of the current map.
when this button is pressed, I am storing the last annotation in a NSMutable array.
then remove the last annotation from mapview and drop one pin at the centre of map
Code I have done for this part is as follows:
function for dropping the pin
- (void)PinDropwithlatitude:(double)lat longitude:(double)longi droptitle:(NSString *)title
{
CLLocationCoordinate2D theCoordinate;
theCoordinate.latitude = lat;
theCoordinate.longitude = longi;
MKCoordinateRegion region;
region.center.latitude = theCoordinate.latitude;
region.center.longitude = theCoordinate.longitude;
//Set Zoom level using Span
MKCoordinateSpan span;
span.latitudeDelta =0.005;
span.longitudeDelta =0.005;
region.span = span;
[MapView setRegion:region animated:YES];
SetLat =lat;
SetLong =longi;
DDAnnotation *annotation = [[[DDAnnotation alloc] initWithCoordinate:theCoordinate addressDictionary:nil] autorelease];
annotation.title = title;
annotation.subtitle = [NSString stringWithFormat:#"%f %f", annotation.coordinate.latitude, annotation.coordinate.longitude];
[MapView addAnnotation:annotation];
}
when I press centre button I am doing the following code and store last array in annotation.
-(IBAction)CenterPressed:(id)sender
{
//40.439631,-3.698273 -spain centre
[lastAnnotation addObjectsFromArray:MapView.annotations];
NSLog(#"last annotation array=%#",lastAnnotation);
for (id annotation in [MapView annotations])
{
if ([annotation isKindOfClass:[MKUserLocation class]])
{
continue;
}
[MapView removeAnnotation:annotation];
}
[self PinDropwithlatitude:SetLat longitude:SetLong
droptitle:NSLocalizedString(#"Title", nil)];
}
the log for the array is showing me the
last annotations you can see below::
last annotation array=(
"<+40.43963100,-3.69827300> +/- 0.00m",
"<+40.43923187,-3.68722200> +/- 0.00m",
"<+40.43792343,-3.67670774> +/- 0.00m",
"<+40.43772888,-3.66711617> +/- 0.00m"
)
2)UNDOButton: which removes the currently placed annotation and redrop the previous annotation, for that i have removed the annotaion from mapview, and redrop the annotation last annotation from array which i have maintained previously,using the code:
-(IBAction)undoPressed:(id)sender
{
if ([lastAnnotation count]>0)
{
int countAnn = [lastAnnotation count];
[MapView removeAnnotation:[lastAnnotation objectAtIndex:countAnn-1]];
//[MapView delete:[lastAnnotation objectAtIndex:countAnn-1]];
[lastAnnotation removeObjectAtIndex:countAnn-1];
double latitude = [[[lastAnnotation objectAtIndex:[lastAnnotation count]-1] annotation]coordinate].latitude;
double longitude = [[[lastAnnotation objectAtIndex:[lastAnnotation count]-1]annotation]coordinate].longitude;
NSLog(#"count = %d",[lastAnnotation count]);
[self PinDropwithlatitude:latitude longitude:longitude droptitle:NSLocalizedString(#"Title", nil)];
}
}
but when i press the undo button it crashes with the following error
-[DDAnnotation annotation]: unrecognized selector sent to instance 0x79b8f40
I don't get to know, where exactly the problem arises. can any one please help me to point out my mistake in the above code.
thanks
can you try
[lastAnnotation lastObject]
instead of
[[lastAnnotation objectAtIndex:[lastAnnotation count]-1]
like
[MapView removeAnnotation:[lastAnnotation lastObject]];
[lastAnnotation removeObject:[lastAnnotation lastObject]];
I am trying to "uncenter" the map view and remove all annotations. the reason for this is that the mapView will be used by different view controllers to display different annotations and locations. What's happening now is that i am using the "remove annotations" method and i removes them, but the map stays centered on the spot and thus when the new annotations come in, it does not move. Is there a way to reset the region and if so, what value do i reset it to. I tried nil, zero and some calculated value but "core animation" says they are all invalid. how do i get that to zoom out and back in on my new annotations?
here is some code
-(void)recenterMap {
NSArray *coordinates = [_mapView valueForKeyPath:#"annotations.coordinate"];
CLLocationCoordinate2D maxCoord = {-90.0f, -180.0f};
CLLocationCoordinate2D minCoord = {90.0f, 180.0f};
//NSLog(#"%#", [coordinates description]);
for (NSValue *value in coordinates) {
CLLocationCoordinate2D coord = {0.0f, 0.0f};
[value getValue: &coord];
if(coord.longitude > maxCoord.longitude) {
maxCoord.longitude = coord.longitude;
}
if(coord.latitude > maxCoord.latitude){
maxCoord.latitude = coord.latitude;
}
if(coord.longitude < minCoord.longitude){
minCoord.longitude = coord.longitude;
}
if(coord.latitude < minCoord.latitude){
minCoord.latitude = coord.latitude;
}
}
MKCoordinateRegion region = {{0.0f, 0.0f}, {0.0f, 0.0f}};
region.center.longitude = (minCoord.longitude + maxCoord.longitude) / 2.0;
region.center.latitude = (minCoord.latitude + maxCoord.latitude) / 2.0;
region.span.longitudeDelta = maxCoord.longitude - minCoord.longitude;
region.span.latitudeDelta = maxCoord.latitude - minCoord.latitude;
[_mapView setRegion: region animated: YES];
}
Thats the recenter methos i'm using
- (MKAnnotationView *)mapView: (MKMapView *)mapView viewForAnnotation: (id <MKAnnotation>)annotation{
MKAnnotationView *view = nil;
if(annotation != mapView.userLocation){
Annotation *schoolAnn = (Annotation*)annotation;
view = [self.mapView dequeueReusableAnnotationViewWithIdentifier:#"schoolLoc"];
if(nil == view){
view = [[[MKPinAnnotationView alloc] initWithAnnotation:schoolAnn reuseIdentifier:#"schoolLoc"]autorelease];
}
[(MKPinAnnotationView *)view setAnimatesDrop:YES];
[view setCanShowCallout:YES];
}
else {
[self recenterMap];
}
return view;
}
This "else" piece waits until the blue marble drops in then recenters the map. The problem i have with that part is that when i go back to the previous View Controller i remove all annotations, so when i come back in the User location (for some reason) does not pop back in. How do i get this to pop back in?
thanks in advance guys
Got the first part, made it zoom out again by just calling a function i made that set the region up to be over the US.
-(void)unCenterMap{
MKCoordinateRegion region2 = {{0.0f, 0.0f}, {0.0f, 0.0f}};
region2.center.longitude = (-98.151855); //coordinate for approximately the center of the US
region2.center.latitude = 39.402244;
region2.span.longitudeDelta = 3.0;
region2.span.latitudeDelta = 3.0;
[_mapView setRegion: region2 animated: YES];
}
The second part still baffles me, how do I get that location to pop in again?