I am new to MKMapView. I implemented a mapView which is looking good. But i was planning to add points or custom image as point in MapView. I can implement it with the help of MKAnnotation, but when i read MKOverlay it was mentioned that Overlays are also annotations. So whats the difference between these two??
Thanks in advance,
aby
In a nutshell, MKAnnotation is based on a point (x,y). MKOverlay is based on an area, bounded by a rectangle.
An MKAnnotation is simply a point on the map, often represented with a red pin icon (you'll see these if you search for a location in Apple's Maps app on iOS), whereas an MKOverlay is another layer over the map to display extra information. A good example of this could be the traffic overlay displayed on the map in US regions to indicate the current level of traffic.
You'd want to use an MKAnnotation in situations where you need to show the user a specific point on a map, but if you want to display more information to them over a larger area, go with an MKOverlay.
Apple uses an MKOverlay to display shipping routes for boats in their WWDC video on the topic (Session 127 – Customizing Maps with Overlays). That would be a good place to learn the full difference between the two, and how to use overlays correctly.
Related
I'm hoping for a straightforward way to display up to 200 points in a Map at once without degrading performance when the user is zoomed out and all of them are on the screen.
We have a draw order of priority and the most important ones are above the others. How can I hide the ones underneath until the user zooms into a specific area?
you can use these delegate methods to determine which region and the zoom level is being shown and show the points accordingly...
– mapView:regionWillChangeAnimated:
– mapView:regionDidChangeAnimated:
refer apple docs for more info..
I am interested in adding an option to my GIS Map application, the ability to draw Polygon, circle, polyroutes overlays for the user to search data within.The problem is that I've read and tested codes of how to draw an overlay, but they are always static.I want it to be dynamic, with dynamic center and points (or radius) set by the user on click.A mystery for me.(I'm a beginner in iPhone programming, this is my first app.)And I'm not using and don't want to use things like ArcGIS API for iPhone.I would appreciate any help.
To let the user "draw" an arbitrary polygon on the map, one approach is to use draggable annotations that represent the corners of the polygon. Provide an "Add Corner" button and some kind of Remove Corner button on each annotation.
See my answer to User creating a box on MKMapView for some more details. On that question though, the OP actually ended up using another solution described in the comments which would work well if the polygons are always rectangles.
For implementing a button in an annotation view (if you want a "Remove Corner" button on the annotations), see my answer to How to get click event from a button added over MKAnnotationView.
Once you a have a polygon or other overlay on the map, dragging it by direct touches may only be possible by adding a gesture recognizer to the map (with its own scrolling turned off) and using a custom MKOverlay and MKOverlayView that allow coordinate changes. Adding a gesture recognizer directly to an MKOverlayView doesn't seem to work and the built-in overlay classes don't allow changes to coordinates.
An alternative to moving by direct touches is putting some controls on the side (Up/Down/Left/Right/etc buttons) that modify the custom overlay.
The Apple sample app Breadcrumb gives an example of a custom overlay/view for a path. In WWDC 2010, the sample app LocationReminders gives an example of a custom overlay/view for a circle that can move and resize.
Finally, when you do a search for businesses, you could use the overlay's boundingMapRect (which is always a rectangle regardless of the overlay's shape) as the bounding box for the initial search and then check if the coordinate of each business found is in the overlay's actual shape using the answer to How to determine if an annotation is inside of MKPolygonView (iOS).
What is the meaning of term OverlayView in iPhone can any one give me detailed description
From Apple documentation:
The MKOverlay protocol defines a specific type of annotation that represents both a point and an area on a map. Overlay objects are essentially data objects that contain the geographic data needed to represent the map area. For example, overlays can take the form of common shapes such as rectangles and circles. They can also describe polygons and other complex shapes.
You use overlays to layer more sophisticated content on top of a map view. For example, you could use an overlay to show the boundaries of a national park or trace a bus route along city streets. The Map Kit framework defines several concrete classes that conform to this protocol and define standard shapes.
Because overlays are also annotations, they have similar usage pattern to annotations. When added to a map view using the addOverlay: method, that view detects whenever the overlay’s defined region intersects the visible portion of the map. At that point, the map view asks its delegate to provide a special overlay view to draw the visual representation of the overlay. If you add an overlay to a map view as an annotation instead, it is treated as an annotation with a single point.
For more info see documenation of MKOverlay and MKOverlayView
Overlay provides you a layer on top of the map so that you can draw something on it(Mostly polygons, lines, points).
To know more see MKOverlay MKOverlayView Apple's Documentation
This tutorial can help you
FYI: MKOverlay will work on iOS4 and after
I want to make an app that partially mimics some of the behavior the standard map application has. This has proven difficult. First of all, I don't understand how you make annotations movable. How exactly do you do this?
Second: how do you search for locations?
Moving annotations
I'm assuming you're after the behavior of Maps.app where you tap and hold on to a pin to move it around freely. As far as I know, there is no built in way of moving annotations around. Since annotations are subclasses of UIView though, you can draw them where and how you'd like. You could for example detect a tap-n-hold on the annotation, and when "unlocked" change the centerOffset value of your annotation to move it around with the touch. When the user lets go of the the view, you can note the position on the screen, and use the MKMapView method convertPoint:toCoordinateFromView: to get the coordinates that the pin was released.
Search for location
What you are looking for is called Forward Geocoding. Unfortunately, MapKit only comes with Reverse Geocoding (the process of converting GPS coordinates to country/city/street/etc). There is, however, several alternatives. Here's a few ways:
http://code.google.com/apis/maps/documentation/geocoding/index.html
http://cloudmade.com/products/iphone-sdk
http://www.geonames.org/export/web-services.html
http://developer.yahoo.com/maps/rest/V1/geocode.html
Note that many geocoding APIs are licensed under Creative Commons, or similar licenses.
You should be able to get drag-and-drop annotations going with the help of this blog post. I used it to do the same thing, and it was pretty simple to get going.
MapKit annotation drag and drop with callout info update
I want to draw a tile-based overlay on top of a MKMapView, but there's no obvious way to do this.
This appears to be tricky since you can zoom to any level with MKMapView (unlike Google Maps).
Has anyone attempted to do this?
Incase this question is still getting views readers should check out the HazardMap and TileMap demo code from WWDC2010.
I'm working on a game where I need to overlay objects on the map and have them scroll and zoom with the map.
Using annotation views I've been able to solve the first problem and partially solve the second problem. Annotations automatically move with the map. For scaling them, I use the mapView:regionDidChangeAnimated: delegate method to resize my annotations after a zoom event. The problem is that the annotations don't rescale until after the zoom gesture is complete.
I can think of two approaches other than filing a bug with Apple requesting that they provide an API for map overlays:
Put a (mostly invisible) view over the top of the MKMapView that intercepts zoom and scroll events, handles them, and passes them on to the map view.
Customize the open-source RouteMe library with tiles from Open Street Map or CloudMade (the former is slow, the latter costs money). But it's fully open source so you should be able to do overlays to your heart's content. You could also run your own tile server that does the tile overlays on the server.
Something I discovered later:
http://www.gisnotes.com/wordpress/2009/10/iphone-devnote-14-drawing-a-point-line-polygon-on-top-of-mkmapview/
Not quite a tile-based solution, but interesting nonetheless.