Comparing speed values issue(what ever i am getting from CLLocationManager)

Question

I am having little bit confused regarding this way of asking question

Any how i am mentioning my query with support of image here. Can you please help me out regarding this issue

Step 1: I have an requirement like: By using CLLocationManger delegate methods i fetched speed value like:

- (void)startLocationUpdates{
locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
locationManager.distanceFilter = kCLDistanceFilterNone;
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
locationManager.pausesLocationUpdatesAutomatically = YES;
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0)
    [locationManager requestWhenInUseAuthorization];
[locationManager startUpdatingLocation];
}
#pragma mark
#pragma mark - CLLocationManagerDelegate
 - (void)locationManager:(CLLocationManager *)manager
 didUpdateLocations:(NSArray *)locations{
float speed = locationManager.location.speed;
float speedInKmph = speed * 3.6;   // to convert the speed into kmph.
NSString *speedValue =[NSString stringWithFormat:@"%.f Kmph ",speedInKmph];
self.currentSpeedLblRef.text = speedValue;
self.maxSpeedLblRef.text = speedValue;
}

Step 2: currentSpeedLblRef,maxSpeedLblRef --> these are my UILabels

Example: Now i am driving a car --> For the first time i opened the app and i got the current speed of car(like: 120 Kmph) and then i need to display same value in "maxSpeedLblRef"(120 Kmph) also

After some time my current speed of car if 50 Kmph. But i need to display value in "maxSpeedLblRef" is --> Max value --> means 120 kmph . Because already i was getting 120 kmph value for previos

After that If my current speed of car if 180 kmph --> I need to show "maxSpeedLblRef" valu like: 180 Kmph. Because it is the latest one compare to 120 Kmph

After Close the app and then

If i reopen the app i want to show the vale like "maxSpeedLblRef" --> 180 Kmph. Because this value is the previous saved value

HERE IS MY SOURCE CODE:Click here link

Answer 1

you are missing a few simple things here!

You need to store the max speed for comparison - all you're doing here is is updating the label with the current value every time. Set up a class-level attribute, initial value = 0, and update it whenever current speed > max speed.

There are a few ways you can store the max value so that it's there when you next open the app. Probably easiest to go with user defaults. There are many tutorials available - try this one http://code.tutsplus.com/tutorials/ios-sdk-working-with-nsuserdefaults--mobile-6039

OK - using your project code, here's what you need.

Update your ViewController.h to this

//  ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController
@property (weak, nonatomic) IBOutlet UILabel *currentSpeedLblRef;
@property (weak, nonatomic) IBOutlet UILabel *maxSpeedLblRef;

// you need to store the max speed
@property float speedMax;

-(void)loadDefaults;
-(void)storeDefaults;

@end

and then in the VIewController.m, replace the viewDidLoad with this

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    [self loadDefaults];

    [self startLocationUpdates];
}

update the locationManager function to this

- (void)locationManager:(CLLocationManager *)manager
 didUpdateLocations:(NSArray *)locations{
    float speed = locationManager.location.speed;
    float speedInKmph = speed * 3.6;   // to convert the speed into kmph.
    NSString *speedValue =[NSString stringWithFormat:@"%.f Kmph ",speedInKmph];
    self.currentSpeedLblRef.text = speedValue;

    if (speedInKmph > self.speedMax)
    {
        self.speedMax = speedInKmph;

        [self storeDefaults];
    }
    NSString *speedMaxValue =[NSString stringWithFormat:@"%.f Kmph ",self.speedMax];

    self.maxSpeedLblRef.text = speedMaxValue;
}

and, finally add the load / store functions

- (void)loadDefaults
{
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    self.speedMax = [defaults floatForKey:@"SpeedMax"];
}

- (void)storeDefaults
{
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    [defaults setFloat:self.speedMax forKey:@"SpeedMax"];
    [defaults synchronize];
}