iPhone应用程序 - 如何只获取当前位置一次并存储用于另一个功能？

Question

在过去的两周里,我一直在研究这个问题 - 我有一个应用程序,它在地图上显示从起点到目的地点的清晰路线.目标点是用户地址(由用户在我们设置的设置菜单中定义/输入),如果我硬编码起点,地图,路线和应用程序都可以正常工作.一旦我尝试实现任何涉及使用cllocation或cllocationmanager的东西,它崩溃并给我一个线程错误(有3个).

这是当前视图控制器头和实现文件:

#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>
#import "MapView.h"
#import "Place.h"
#import <CoreLocation/CoreLocation.h>


@interface HomeMapViewController : UIViewController <MKMapViewDelegate, CLLocationManagerDelegate>{

    IBOutlet UILabel *HomeAddressLabel;

}

@property (weak, nonatomic) IBOutlet MKMapView *MapView;
@property (strong, nonatomic) IBOutlet CLLocationManager *location;
@end

实施文件:

#import "HomeMapViewController.h"



@interface HomeMapViewController ()

@end


@implementation HomeMapViewController
@synthesize MapView;
@synthesize location;
double lat = 37.331706;
double lon = -122.030598;
- (id)initWithNibNameNSString *)nibNameOrNil bundleNSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}


- (void)viewDidLoad
{
    //Retrieve saved address before view loads
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSString *HomeAddress = [defaults objectForKey:@"HomeAddress"];
    NSString *HomeCity = [defaults objectForKey:@"HomeCity"];
    NSString *HomeProvince = [defaults objectForKey:@"HomeProvince"];
    NSString *HomeZip = [defaults objectForKey:@"HomeZip"];
    NSString *HomeCountry = [defaults objectForKey:@"HomeCountry"];
    NSString *HomeAddressFull = [NSString stringWithFormat:@"%@, %@, %@, %@, %@", HomeAddress, HomeCity, HomeProvince, HomeZip, HomeCountry];

    //Set address label to saved address values
    HomeAddressLabel.text = HomeAddressFull;



    //Map Route Code

        MapView* mapView = [[MapView alloc] initWithFrame:
                        CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
        //Shows user location

    [self.MapView setShowsUserLocation:YES];
    //set which mapview to show
        [self.MapView addSubview:mapView];

    self.location = [[CLLocationManager alloc]init];
    location.delegate = self;
    location.desiredAccuracy=kCLLocationAccuracyBest;
    location.distanceFilter = kCLLocationAccuracyBestForNavigation;//constant update of device location
    [location startUpdatingLocation];


    Place* start = [[Place alloc] init];
    start.name = @"Start Location";
    start.description = @"You started here.";
    //^should be changed to current location once that is implemented
    //start.latitude =    37.331706;
    //start.longitude = -122.030598;
    start.latitude = lat;
    start.longitude = lon;
    //start.latitude = location.location.coordinate.latitude;
    //start.longitude = location.location.coordinate.longitude;


    //Geocoder Code
    CLGeocoder *geocoder = [[CLGeocoder alloc] init];
    [geocoder geocodeAddressString:HomeAddressFull completionHandler:^(NSArray *placemarks, NSError *error) {
        if (error) {
            NSLog(@"Error: %@", [error localizedDescription]);
            return;
        }

        for (id object in placemarks) {
            CLPlacemark *placemark = object;



            Place* destination = [[Place alloc] init];
            destination.name = @"Destination";
            destination.description = [NSString stringWithFormat:@"%@, %@, %@", HomeAddress, HomeCity, HomeProvince];
            destination.latitude = placemark.location.coordinate.latitude;
            destination.longitude = placemark.location.coordinate.longitude;

            [mapView showRouteFrom:start toestination];
        }
    }];


    [super viewDidLoad];

}

- (void)locationManagerCLLocationManager *)manager didUpdateToLocationCLLocation *)newLocation fromLocationCLLocation *)oldLocation{
    [manager stopUpdatingLocation];

}



//************NEW METHOD
-(void)locationManagerCLLocationManager *)manager didFailWithErrorNSError *)error{
    NSString *msg = @"Error obtraining location:";
    UIAlertView *alert;
    alert = [[UIAlertView alloc]
             initWithTitle:@"Error"
             message:msg delegate:self
             cancelButtonTitle:@"OK"
             otherButtonTitles: nil];
    [alert show];

}

- (void)viewDidUnload
{
    [self setMapView:nil];
    HomeAddressLabel = nil;
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}

- (BOOL)shouldAutorotateToInterfaceOrientationUIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}


@end

我基本上想问一下是否有人可以帮助我了解如何获取用户当前位置坐标并将其存储为start.latitude和start.longitude值,以便路径显示来自用户当前位置的路径到他们的目的地.当用户移动时,路线不应该更新自己,我只想在用户当前位置和目的地上有一个注释/地标(就像我有的那样)然后蓝点(也就是用户)将能够看到自己沿着他们要走的路线前进.我已经在这里尝试了所有的建议 - 有些没有工作,有些只工作一次,然后它再次无法工作(甚至在重置模拟器内容后!).一些链接是相关的,但非常过时,所以那里的方法不起作用.

在这里,我认为让用户当前的位置坐标将是这个功能更容易的任务!

Answer 1

.h文件

#import <CoreLocation/CoreLocation.h>

@property (nonatomic,retain) CLLocationManager *locationManager;

.m文件

- (NSString *)deviceLocation 
{
    NSString *theLocation = [NSString stringWithFormat:@"latitude: %f longitude: %f", self.locationManager.location.coordinate.latitude, self.locationManager.location.coordinate.longitude];
    return theLocation;
}

- (void)viewDidLoad
{
    self.locationManager = [[CLLocationManager alloc] init];
    self.locationManager.distanceFilter = kCLDistanceFilterNone; 
    self.locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters; // 100 m
    [self.locationManager startUpdatingLocation];
}

Answer 2

这样做的简单方法是将起始当前位置存储在NSUserDefaults中

     NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    [defaults setObject:latitude forKey:@"starLatitude"];
    [defaults setObject:longitude forKey:@"starLongitude"];
[defaults synchronize];

然后您可以通过以下方式获得纬度和经度:

NSString *lati = [defaults objectForKey:@"starLatitude"];