Question

我已经在地图视图上编了几个注释，效果很好。但是，由于某些原因，当我在设备上单击我的MapView时，请单击“离开”，然后返回到MapView，由于某种原因它不会放大到用户的位置（它只显示整个世界的地图）。有谁知道为什么？请参阅下面的代码：

MapViewController.h

#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>

@interface MapViewController : UIViewController  <MKMapViewDelegate> 

    @property (nonatomic, strong) IBOutlet MKMapView *mapView;
    @property (nonatomic, retain) NSMutableArray *dispensaries;
    @property (nonatomic, retain) NSMutableData *data;

@end

MapViewController.m

#import "MapViewController.h"
#import "MapViewAnnotation.h"
#import "JSONKit.h"

@implementation MapViewController
@synthesize mapView;
@synthesize dispensaries;
@synthesize data;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)didReceiveMemoryWarning
{
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

    // Release any cached data, images, etc that aren't in use.
}

#pragma mark - View lifecycle

- (void)viewDidLoad {

    NSLog(@"Getting Device Locations");

    NSString *hostStr = @"http://stylerepublicmagazine.com/dispensaries.php";
    NSData *dataURL = [NSData dataWithContentsOfURL:[NSURL URLWithString:hostStr]];
    NSString *serverOutput = [[NSString alloc] initWithData:dataURL encoding: NSASCIIStringEncoding];
    NSLog(@"server output: %@", serverOutput);
    NSMutableArray *array = [[serverOutput objectFromJSONString] mutableCopy];
    dispensaries = [serverOutput objectFromJSONString];
    NSLog(@"%@", [serverOutput objectFromJSONString]);
    for (NSDictionary *dictionary in array) {
        assert([dictionary respondsToSelector:@selector(objectForKey:)]);

        CLLocationCoordinate2D coord = {[[dictionary objectForKey:@"lat"] doubleValue], [[dictionary objectForKey:@"lng"] doubleValue]};

        MapViewAnnotation *ann = [[MapViewAnnotation alloc] init];
        ann.title = [dictionary objectForKey:@"Name"];
        ann.subtitle = [dictionary objectForKey:@"Address1"];
        ann.coordinate = coord;
        [mapView addAnnotation:ann];

        [mapView setMapType:MKMapTypeStandard];
        [mapView setZoomEnabled:YES];
        [mapView setScrollEnabled:YES];

        self.mapView.delegate = self;
    }
}

- (void)mapView:(MKMapView *)mapView didUpdateUserLocation:(MKUserLocation *)userLocation
{
    MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(userLocation.coordinate, 2000, 2000);
    [self.mapView setRegion:[self.mapView regionThatFits:region] animated:YES];

    MKPointAnnotation *point = [[MKPointAnnotation alloc] init];
    point.coordinate = userLocation.coordinate;
    point.title = @"You Are Here";
    point.subtitle = @"Your current location";

    [self.mapView addAnnotation:point];
}


- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {

    for (MapViewAnnotation *annotation in self.mapView.annotations) {
        CLLocationCoordinate2D coord = [annotation coordinate];
        CLLocation *annotationLocation = [[CLLocation alloc] initWithLatitude:coord.latitude longitude:coord.longitude];
        annotation.distance = [newLocation distanceFromLocation:annotationLocation];
    }
}

// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;

// Do any additional setup after loading the view from its nib.

- (void)viewDidUnload
{

}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    // Return YES for supported orientations
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

@end

Answer 1

这将是在模拟器上运行应用程序的一种表现形式（因为用户的位置不会像在设备上那样改变）。你试过在设备上运行吗？很可能（除非你还有其他事情发生），你会得到很多didUpdateUserLocation次点击，因此你不会遇到与模拟器上相同的用户体验问题。

如果失败，您还可以viewDidLoad设置地图的region。也许使用Core Location的CLLocationManager。

我怀疑你没有在设备上运行它，因为当我解释didUpdateUserLocation时，每次用户的位置发生变化时，这都会添加另一个注释。这在设备上尤其成问题，因为随着GPS的升温，您最终会得到一系列的位置变化，因为它变得越来越准确（通常会减少horizontalAccuracy。

我认为你真的不想在你的地图上看到十几个“你在这里”的注释。您可能希望确保删除任何先前的位置（或者仅依靠在IB中打开“显示用户位置”时设置的MKMapView默认用户注释或设置showsUserLocation属性）。

另请注意，您可以将userTrackingMode设置为MKUserTrackingModeFollow，并自动为您设置区域（假设（a）用户已授予您权限;以及（b）用户已足够小区/ WiFi / GPS信号）。

MapView放大到用户位置，但是当我更改视图并返回到mapview时，放大不起作用？

1 个答案: