iOS 8中的MapKit無法運行

Question

我正在構建一個在MapView中顯示POI的iOS應用程序，但是首先我可以顯示地圖，而對於iOS8，這是一個問題。 我在這個站點上讀了很多問題，但是即使代碼看起來正確，也沒有一個在我的應用程序上運行。

我將以下代碼輸入到myapplicationTest-info.plist中

<key>NSLocationAlwaysUsageDescription</key>

而file.m中的代碼是這樣的：

#import "MapViewController.h"

#define IS_OS_8_OR_LATER ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0)

@interface MapViewController ()

@end

@implementation MapViewController
@synthesize mapView = _mapView ;


- (void)viewDidLoad
{

    [super viewDidLoad];

    self.mapView.delegate = self;
    self.locationManager.delegate = self;
    self.locationManager = [[CLLocationManager alloc] init];
if (IS_OS_8_OR_LATER) {
    //[self.locationManager requestWhenInUseAuthorization];
    [self.locationManager requestAlwaysAuthorization];
}

   [self.locationManager startUpdatingLocation];

   self.mapView.showsUserLocation = YES;
   [mapView setMapType:MKMapTypeStandard];
   [mapView setZoomEnabled:YES];
   [mapView setScrollEnabled:YES];
}

-(void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:YES];

    self.locationManager.distanceFilter = kCLDistanceFilterNone; //Whenever we move
    self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
    [self.locationManager startUpdatingLocation];
    NSLog(@"%@", [self deviceLocation]);

    //View Area
    MKCoordinateRegion region = { { 0.0, 0.0 }, { 0.0, 0.0 } };
    region.center.latitude = self.locationManager.location.coordinate.latitude;
    region.center.longitude = self.locationManager.location.coordinate.longitude;
    region.span.longitudeDelta = 0.005f;
    region.span.longitudeDelta = 0.005f;
    [mapView setRegion:region animated:YES];

}

- (void)mapView:(MKMapView *)mapView didUpdateUserLocation:(MKUserLocation *)userLocation
{
    MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(userLocation.coordinate, 800, 800);
    [self.mapView setRegion:[self.mapView regionThatFits:region] animated:YES];

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

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


@end

錯誤在哪里？

為什么不運行？

Answer 1

您需要為NSLocationAlwaysUsageDescription鍵提供一個值， NSLocationAlwaysUsageDescription鍵是描述您的應用為何要使用位置服務的字符串-

例如 -

<key>NSLocationAlwaysUsageDescription</key>
<string>FindMeDonuts will use your location to identify nearby donut shops</string>

另外，與其檢查iOS版本，不如檢查CLLocationManager是否響應授權選擇器-

if ([self.locationManager respondsToSelector:@selector(requestAlwaysAuthorization)]) {
        [self.locationManager requestAlwaysAuthorization];
}

最終，這不會阻止地圖的更新，但這沒有意義-在分配和初始化它之前，您正在將委托分配給CLLocationManager 。

你應該說 -

self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate=self;

Answer 2

我不知道我是否理解你的問題。

如果您的問題是關於地圖未顯示，則需要設置地圖框架。

self.mapView.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);

希望我能幫助你

Answer 3

最好的方法是使用CLLocationManagerDelegate提供的-locationManager：didUpdateLocations方法。

- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations 
{
    [self.locationManager stopUpdatingLocation];
    // Move this line here
    self.mapView.showsUserLocation = YES; 
}

在[self.locationManager startUpdatingLocation]調用[self.locationManager startUpdatingLocation]后，您不應將self.mapView.showsUserLocation設置為YES ，因為尚未批准使用位置服務的權限。 在將self.mapView.showsUserLocation設置為YES之前，使用委托從系統等待/獲取位置更新。

Answer 4

您還需要啟用位置服務

if([CLLocationManager resolveClassMethod:@selector(locationServicesEnabled)]) {
    [CLLocationManager locationServicesEnabled];
}