I have create a program to find out my current location using IOS corelocation framework.It works fine.
I need to create a program that list nearest branchaes of a shop chain, while a user travel with the phone.My data base contains the branches details with Latitude and lognitude.How i compare with these details to find out the nearest branch.
Help is highly appreciated.Anybody knows any example program
Thanks,
VKS
You can make use of distanceFromLocation: method of CLLocation.
distanceFromLocation:
Returns the distance (in meters) from the receiver’s location to the
specified location.
(CLLocationDistance)distanceFromLocation:(const CLLocation
*)location
Parameters
location
The other location.
Return Value
The distance (in meters) between the two locations.
Discussion
This method measures the distance between the two locations by tracing
a line between them that follows the curvature of the Earth. The
resulting arc is a smooth curve and does not take into account
specific altitude changes between the two locations.
Availability
Available in iOS 3.2 and later.
By using this method to get the distances of the shops with your current location, you can then sort the list based on the distance to get the nearest branch
VKS, I got to solve the exact same problem too now (using apptarget iOS 5). Do you have any example code / snippets / tips to share for this problem, that I assumed you solved a long time ago? The above is very good explanation from 7KV7, but some examples will speed up my process a lot. Thank's :-)
Related
I would like to log relative altitude changes on apple watch 3 using the CMAltimeter class. On simulator the isRelativeAltitudeAvailable() function returns false, so I tested on real device. Here I noticed, that information is provided, but by far too much alt meters (e.g. making 100-1000 m just by moving around on same level). What point I am missing?
- expecting that first point is 0
- following relativeAltitudes are changes relative to this in meters.
Thanks for you help!
You should use CLLocation see this for more information.
I am developing a project in augmented reality where a compass shows the direction to the destination.That works fine but i want to check whether the current heading is pointing towards the destination or not.
Can any one suggest me a method to do it?
I have searched a lot in Google couldn't find any method?
Thanks in advance
You need the absolute bearing from your location to your target location
Unfortunately CLLocation doesn't have a call for this but you can find the algo in this question.
CLLocation Category for Calculating Bearing w/ Haversine function
So lets say the bearing is 90 degrees
Then you get the phone bearing to north.
While you are getting location updates you also have course update with CLLocation.
The course might also be 90 degrees
SO find the difference between the two, 90 - 90 = 0! you are dead on target :) You will need to rationalise the numbers to 0 - 360 in the event say you are facing north (0 degrees) and your target is behind you (180 degrees) resulting in -180. If you end up with a negative number just add 360.
I find the magnetic field compass to be very very fidgety, so it looks much nicer if you have some sort of exponential moving average for changes in the phones bearing.
I'm building an augmented reality game, and working with CLLocation is rather cumbersome.
Is there some way to locally approximate CLLocation as XYZ coordinate, expressed in meters with the origin starting at some arbitrary point (for example the initial position when the game was started)?
Lets say I'm working with a 1 mile radius and do not really care about the curvature of the earth. Is it possible to approximate or somehow simplify the location based calculations for local position tracking?
Alternatively, is there a coordinate system that can be used with CLLocation that also incorporates the roll, pitch, yaw of the CMAttitude as well as compass orientation?
Clarification: As far as I understand, the problem with latitude and longitude is that their units vary in size, depending on the position on the globe. I should've specified that X,Y,Z should be in standard units, like meters or feet.
Thank you!
The Haversine formula may be useful.
I found a good article on it at http://www.jaimerios.com/?p=39 with code examples.
You could get the initial point at the app's launch and calculate the relative points based on the user coordinates as he or she moves. Admittedly, this is not super elegant, but if you are just trying to do some simple comparisons based on the user's location relative to an arbitrary origin, this should work. For the Z, Alex Stone's suggestion of calculating it based on the altitude should be fine.
In my application i am having 4 places with its longitude and altitude(Given).Now i want to find the nearest place from user.
So anyone can tell me the solution for it or provide me some source code or demo for this.
Thanks to all
Create an CLLocation of the points:
CLLocation* locationx = [[CLLocation alloc] initWithLatitude:lat longitude:lon];
And the compare the points with:
double distance = [userposition distanceFromLocation:locationx];
Keep the nearest location.
Edit:
If you really mean "longitude and altitude" then I dont know how.
just took 10 seconds to ask google and find this, wich describes how to calculate the distance beween two points given latitude and logitude:
http://www.movable-type.co.uk/scripts/latlong.html
all you have to do is calculate the distance to all 4 points and choose the lowest one.
ETDI: i'm sure you're also given the latitude, otherwise you won't even have specific coordinates. if this wasn't a type and you really have to take the altitude into account, take a look at this question at google answers
picknick describes a native class method.
This is probably going to use the Haversine formula (search the web or stackoverflow for discussions) to measure distances.
In my experience, writing your own Haversine is usually faster than using a system/app-provided one, although this is on Windows where COM overhead can be "problematic" as it were!
The Haversine (and many similar geometry-on-the-Earth) formulae can be found here:
http://williams.best.vwh.net/avform.htm
(this is one of my few bookmarks I go back to for reference on a regular basis!)
for example user is at x=0,y=0
Calculate the distance by doing : SquareRoot(x2^2 & y2^2)
You will get a distance. Look through all points and compare which distance is the shortest
I'd like to know (from a high level view) what would be required to take a pdf floor plan of a building and determine where exactly you are on that floor plan using GPS coordinates? In addition to location, the user would be presented with a "turn by turn" directions to another point on the map, navigating down hallways, between cubicles, etc.
Use case: an iPhone app that determined a user's location and guided them to a conference room or person's office in the building.
I realize that this is by no means trivial, but any help is appreciated. Thanks!
It's an interesting problem. When you're using Core Location, you're not necessarily using GPS. Using WiFi and cell tower triangulation, you can get pretty good location results. So from Core Location you get a latitude and longitude fix. (You might also get altitude info, since GPS data is 3-dimensional. You also will get an accuracy value.)
So you have lat and lon. You need to map these coordinates to the PDF plan's coordinates. Assuming that the plan is aligned with the latitude and longitude lines, and that you have a lat-long fix for one of the points on the plan, you need to calculate the x-axis scale and y-axis scale. Then it's some calculations to map the lat-long to x-y coordinates on the PDF plan.
GPS may not be accurate enough for this purpose, especially indoors. Assuming errors on
the order of 10 meters, you'll have difficulty determining which floor the user is on.
Here's a neat (?) idea that might work: can you post some "You are here" placards
at various locations around the building? You could label each one with a unique,
machine-readable location code (maybe a QR code or something similar), then take an
image using the camera, have your app read that image and interpret the location code,
and use that instead of GPS to determine the start location.
GPS inside? That's your first -- and biggest -- hurdle.
Next hurdle is knowing the GPS coordinates of at least three points on that PDF to define the plane of of your map in the real world. (The PDF will need to be to scale, of course.)
So that gives you where you are on the PDF. Now you'll need to figure out some way to determine where you can walk (or where you can't) to get directions.