Help needed regarding CLLocation Manager

Question

Hello everybody,
i am developing a GPS application in which i needs to track the speed of the device/iphone ,i am using the CLCorelocation API's Locate me referral code provided by Apple my problem is that the LocationManager does not updates the current latitude and longitudes thus i am unable to calculate the distance as well as the speed of the device/iphone.
Any kinds of suggestions/code will be highly appreciated please suggest me if i can do something with the Mapkit framework introduced in the sdk 3.0.
thanks in advance

Answer 1

Thanks for your reply i am copying my code what i have implemented and it does not works please have a look at it and let me know what i am doing wrong i will be very helpful to you.
- (void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation
ASafeDriverAppDelegate *appDel1 = (ASafeDriverAppDelegate *)[[UIApplication sharedApplication] delegate];
chklat = newLocation.coordinate.latitude;
chklon = newLocation.coordinate.longitude;
appDel1.maxSpeed=0;
double timeDiff;
NSMutableString *update = [[[NSMutableString alloc] init]autorelease];
// Horizontal coordinates
if (signbit(newLocation.horizontalAccuracy)) {
// Negative accuracy means an invalid or unavailable measurement
[update appendString:LocStr(@"LatLongUnavailable")];
} else {
// CoreLocation returns positive for North & East, negative for South & West
[update appendFormat:LocStr(@"LatLongFormat"), // This format takes 4 args: 2 pairs of the form coordinate + compass direction
fabs(newLocation.coordinate.latitude), signbit(newLocation.coordinate.latitude) ? LocStr(@"South") : LocStr(@"North"),
fabs(newLocation.coordinate.longitude),signbit(newLocation.coordinate.longitude ) ? LocStr(@"West") : LocStr(@"East")];
[update appendString:@"\n"];
[update appendFormat:LocStr(@"MeterAccuracyFormat"), newLocation.horizontalAccuracy];
mShouldStopAndStartLocationServiceAgain = YES;
[update appendString:@"\n\n"];
// Altitude
if (signbit(newLocation.verticalAccuracy)) {
// Negative accuracy means an invalid or unavailable measurement
[update appendString:LocStr(@"AltUnavailable")];
} else {
// Positive and negative in altitude denote above & below sea level, respectively
[update appendFormat:LocStr(@"AltitudeFormat"), fabs(newLocation.altitude), (signbit(newLocation.altitude)) ? LocStr(@"BelowSeaLevel") : LocStr(@"AboveSeaLevel")];
[update appendString:@"\n"];
[update appendFormat:LocStr(@"MeterAccuracyFormat"), newLocation.verticalAccuracy];
[update appendString:@"\n\n"];
//geocoding implementation here........................................................................... .........................................
NSString *ServerUrl=@"http://maps.google.com/maps/geo?";
NSString *restUrl=@"output=csv&oe=utf8&sensor=false&key=ABQIAAAA9nyRoYg0rWpsiVi9iMjoSRQV WFT_Rez40XtsgfvlPpZQQeDyexSS5IUWt7S7bu53pG1lR3fjgcrfxQ";
NSString * URLdata=[NSString stringWithFormat:@"%@q=%f,%f&%@",ServerUrl,newLocation.coordinate.latitude,newL ocation.coordinate.longitude,restUrl];
NSURL *theURL = [NSURL URLWithString:URLdata];
NSURLRequest *myURLRequest = [NSURLRequest requestWithURL: theURL];
NSURLResponse* myURLResponse;
NSError* myError;
NSData* myDataResult = [NSURLConnection sendSynchronousRequest: myURLRequest returningResponse:&myURLResponse error:& myError];
NSString* StreetName;
BOOL val=YES;
StreetName = [[NSString alloc] initWithData:myDataResult encoding:NSASCIIStringEncoding];
//NSLog(@"this is the lenght of the street name %d",[StreetName length]);
if([StreetName length]!=0)
NSLog(@"this is the street name received.............. %@",StreetName);//[StreetName substringFromIndex:6]);
//NSMutableArray *street=[[StreetName substringFromIndex:6] componentsSeparatedByString:@","];
NSMutableArray street=(NSMutableArray*)(NSMutableArray)[StreetName componentsSeparatedByString:@","];
NSString *tempString=[street objectAtIndex:2];
appDel1.currentLocation=[tempString substringFromIndex:1];
NSRange range=[tempString rangeOfString:@" "];
if(range.location==NSNotFound)
val=NO;
//NSLog(@"this is the value of bool in false %d",val);
else
val=YES;
//NSLog(@"this is the vale of bool in true %d",val);
NSString *finalStreet;
NSString *temp2;
temp3=@" ";
if(!val)
finalStreet=[tempString substringFromIndex:1];
NSLog(@"this is the street name %@",finalStreet);
else
NSMutableArray temp1=(NSMutableArray)[tempString componentsSeparatedByString:@" "];
for(int i=1;i<[temp1 count];i++)
temp2=[temp1 objectAtIndex:i];
temp3=[[temp3 stringByAppendingString:@" "] stringByAppendingString:temp2];
finalStreet=[temp3 substringFromIndex:0];
NSMutableArray *speedValues=[appDel1 getSpeedValue:[finalStreet stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]];
if([speedValues count]>0)
if(appDel1.moreThanOneSpeed==YES)
appDel1.maxSpeed=[appDel1 getSpeed:[finalStreet substringFromIndex:0] first:newLocation.coordinate.latitude second:newLocation.coordinate.longitude];
else
appDel1.maxSpeed=[[speedValues objectAtIndex:0]intValue];
//Calculate speed
CLLocationDistance distance;
double calSpeed;
NSTimeInterval difference;
//calculate distance and time elapsed only if we save old location
if(oldLocation != nil)
difference= [[newLocation timestamp] timeIntervalSinceDate:[oldLocation timestamp]];
distance = [newLocation getDistanceFrom:oldLocation];
else{
distance = 0.0;
calSpeed =(distance/difference)*2.23693629;
NSLog(@"Time elapsed is: %f", difference);
NSLog(@"Distance travelled is: %f", distance);
NSLog(@"Speed is: %f", calSpeed);
//save the latest newLocation for calculating the speed
oldLocation = [newLocation retain];
appDel1.distance=distance;
appDel1.time=timeDiff;
[self.delegate displaySpeed:oldLocation.coordinate.latitude second:oldLocation.coordinate.longitude third:newLocation.coordinate.latitude fourth:newLocation.coordinate.longitude];
if(appDel1.speed!=calSpeed)
appDel1.speed=calSpeed;
[appDel1 checkLimitAndSpeed];
the speed and distance returned is always zero as the latitude and longitude remains the same always it does not keep updating.
Thanks