Core Location和MapKit的一些简单使用

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mb5fe18e9fef50b 2013-08-22 14:43:00

文章标签 2d git ide 文章分类 代码人生

Core Location

1. 基本对象是CLLocation，有属性coordinate, altitude, horizontal/vertical Accuracy, timestamp, speed, course

typedef {
CLLocationDegrees latitude; // a double
CLLocationDegrees longitude; // a double
} CLLocationCoordinate2D; // 经纬度

@property (readonly) CLLocationAccuracy horizontalAccuracy; // in meters
@property (readonly) CLLocationAccuracy verticalAccuracy;
kCLLocationAccuracyBestForNavigation;
kCLLocationAccuracyBest;
kCLLocationAccuracyNearestTenMeters;
kCLLocationAccuracyHundredMeters;
kCLLocationAccuracyKilometer;
kCLLocationAccuracyThreeKilometers;

- (CLLocationDistance)distanceFromLocation:(CLLocation *)otherLocation; // in meters 两个位置之间的距离

2. 总是通过CLLocationManager来获取CLLocation（通过其代理），其一般的使用方法为：

（1）检查硬件是否支持你需要的位置更新

（2）创建一个CLLocationManager实例，并设置接收更新的代理对象

（3）根据你的需求对CLLocationManager进行配置

（4）启动CLLocationManager来监视改变。

3. Core Location Manager的一些设置

@property CLLocationAccuracy desiredAccuracy; // always set this as low as possible
@property CLLocationDistance distanceFilter;
- (void)startUpdatingLocation;
- (void)stopUpdatingLocation;
- (void)startMonitoringSignificantLocationChanges;
- (void)stopMonitoringSignificantLocationChanges;

Core Location框架提供了三种用于追踪设备当前位置的服务

The significant-change location
service 提供了低耗电的方法来获取当前位置，当前位置改变时会发出通知
The standard location service 提供了一种可设置的方法来获取当前位置
Region monitoring 监视特定地区的跨越

Listing 1 Starting the standard location service
- (void)startStandardUpdates
{
// 创建location manager
if (nil == locationManager)
locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
　　// 设置获取位置的精确度，越精确越耗电
locationManager.desiredAccuracy = kCLLocationAccuracyKilometer;
// 设置距离过滤器，超过次距离就更新一次位置
locationManager.distanceFilter = 500;
[locationManager startUpdatingLocation];
}

Listing 2 Significant-Change Location Service
- (void)startSignificantChangeUpdates
{
// Create the location manager if this object does not
// already have one.
if (nil == locationManager)
locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
[locationManager startMonitoringSignificantLocationChanges];
}

4. 检查硬件

+ (BOOL)locationServicesEnabled; // has the user enabled location monitoring in Settings?
+ (BOOL)headingAvailable; // can this hardware provide heading info (compass)?
+ (BOOL)significantLocationChangeMonitoringAvailable; // only if device has cellular?
+ (BOOL)regionMonitoringAvailable; // only certain iOS4 devices
+ (BOOL)regionMonitoringEnabled; // by the user in Settings

当程序初次使用位置服务时，会询问用户。可以提供一个string来描述使用目的。如果用户拒绝，则上面所有方法均返回NO

@property (copy) NSString *purpose

5. 获取位置更新

// Delegate method from the CLLocationManagerDelegate protocol.
- (void)locationManager:(CLLocationManager *)manager
didUpdateToLocation:(CLLocation *)newLocation
fromLocation:(CLLocation *)oldLocation
{
// If it's a relatively recent event, turn off updates to save power
NSDate* eventDate = newLocation.timestamp;
NSTimeInterval howRecent = [eventDate timeIntervalSinceNow];
if (abs(howRecent) < 15.0)
{
NSLog(@"latitude %+.6f, longitude %+.6f\n",
newLocation.coordinate.latitude,
newLocation.coordinate.longitude);
}
// else skip the event and process the next one.
}

- (void)locationManager:(CLLocationManager *)manager
didFailWithError:(NSError *)error;
typedef enum {
kCLErrorLocationUnknown = 0,
kCLErrorDenied, // 如果用户拒绝开启位置服务，那么应该停止location manager
kCLErrorNetwork,
kCLErrorHeadingFailure,
kCLErrorRegionMonitoringDenied,
kCLErrorRegionMonitoringFailure,
kCLErrorRegionMonitoringSetupDelayed,
} CLError;

6. Geocoding Location Data

Geocoder对象使用网络服务来将经纬度转换为具体地址信息，iOS当前只支持经纬度转地址信息，不能将位置信息转换为经纬度

创建一个MKReverseGeocoder实例，设置代理，调用start方法。

代理会接受到 reverseGeocoder:didFindPlacemark:和reverseGeocoder:didFailWithError:

@implementation MyGeocoderViewController (CustomGeocodingAdditions)
- (void)geocodeLocation:(CLLocation*)location forAnnotation:(MapLocation*)annotation
{
MKReverseGeocoder* theGeocoder = [[MKReverseGeocoder alloc] initWithCoordinate:location.coordinate];
theGeocoder.delegate = self;
[theGeocoder start];
}
// Delegate methods
- (void)reverseGeocoder:(MKReverseGeocoder*)geocoder didFindPlacemark:(MKPlacemark*)place
{
MapLocation* theAnnotation = [map annotationForCoordinate:place.coordinate];
if (!theAnnotation)
return;
// Associate the placemark with the annotation.
theAnnotation.placemark = place;
// Add a More Info button to the annotation's view.
MKPinAnnotationView* view = (MKPinAnnotationView*)[map viewForAnnotation:annotation];
if (view && (view.rightCalloutAccessoryView == nil))
{
view.canShowCallout = YES;
view.rightCalloutAccessoryView = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
}
}
- (void)reverseGeocoder:(MKReverseGeocoder*)geocoder didFailWithError:(NSError*)error
{
NSLog(@"Could not retrieve the specified place information.\n");
}
@end
@implementation MKMapView (GeocoderAdditions)
- (MapLocation*)annotationForCoordinate:(CLLocationCoordinate2D)coord
{
// Iterate through the map view's list of coordinates
// and return the first one whose coordinate matches
// the specified value exactly.
id<MKAnnotation> theObj = nil;
for (id obj in [self annotations])
{
if (([obj isKindOfClass:[MapLocation class]]))
{
MapLocation* anObj = (MapLocation*)obj;
if ((anObj.coordinate.latitude == coord.latitude) &&
(anObj.coordinate.longitude == coord.longitude))
{
theObj = anObj;
break;
}
}
}
return theObj;
}
@end

MapKit

1. MKMapView 显示地图

2. 地图上可以显示注释（annotation），每个annotation由coordinate，title，subtitle构成，并由MKAnnotationView来显示

3. Annotation可以有一个callout，当annotation view被点击时显示，默认情况下只是显示title和subtitle，不过你可以添加左右accessory views

4. MKMapView显示一个遵守MKAnnotation协议的数组对象

@property (readonly) NSArray *annotations; // contains id <MKAnnotation> objects
<pre name="code" class="plain">MKAnnotation protocol
@protocol MKAnnotation <NSObject>
@property (readonly) CLLocationCoordinate2D coordinate;
@optional
@property (readonly) NSString *title;
@property (readonly) NSString *subtitle;
@end
typedef {
CLLocationDegrees latitude;
CLLocationDegrees longitude;
} CLLocationCoordinate2D;</pre>
<pre></pre>
<pre></pre>
5. 管理map view的annotations的方法
<pre name="code" class="plain">- (void)addAnnotation:(id <MKAnnotation>)annotation;
- (void)addAnnotations:(NSArray *)annotations;
- (void)removeAnnotation:(id <MKAnnotation>)annotation;
- (void)removeAnnotations:(NSArray *)annotations;</pre>
6. MKMapView使用跟TableView类似的方法来重用annotation view
7. Annotations通过MKAnnotationView的子类显示在地图上，默认为MKPinAnnotationView
8. 如果MKAnnotationView的canShowCallout设置为YES，那么点击会显示，同时会调用
<pre name="code" class="plain">- (void)mapView:(MKMapView *)sender didSelectAnnotationView:(MKAnnotationView *)aView;
//This is a great place to set up the MKAnnotationView‘s callout accessory views lazily.
</pre>
9. MKAnnotationViews的创建方法跟tableviewcell在tableview中的创建类似
<pre name="code" class="plain">- (MKAnnotationView *)mapView:(MKMapView *)sender
viewForAnnotation:(id <MKAnnotation>)annotation
{
MKAnnotationView *aView = [sender dequeueReusableAnnotationViewWithIdentifier:IDENT];
if (!aView) {
aView = [[MKPinAnnotationView alloc] initWithAnnotation:annotation
reuseIdentifier:IDENT];
// set canShowCallout to YES and build aView’s callout accessory views here
}
aView.annotation = annotation; // yes, this happens twice if no dequeue
// maybe load up accessory views here (if not too expensive)?
// or reset them and wait until mapView:didSelectAnnotationView: to load actual data
return aView;
}
</pre>
10. MKAnnotationView的一些属性
<pre name="code" class="plain">@property id <MKAnnotation> annotation; // the annotation; treat as if readonly
@property UIImage *image; // instead of the pin, for example
@property UIView *leftCalloutAccessoryView; // maybe a UIImageView
@property UIView *rightCalloutAccessoryView; // maybe a “disclosure” UIButton
@property BOOL enabled; // NO means it ignores touch events, no delegate method, no callout
@property CGPoint centerOffset; // where the “head of the pin” is relative to the image
@property BOOL draggable; // only works if the annotation implements setCoordinate:</pre>
11. 如果你设置一个callout accessory view为一个UIControl
<pre name="code" class="plain">e.g. aView.rightCalloutAccessoryView = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
The following MKMapViewDelegate method will get called when the accessory view is touched ...
- (void)mapView:(MKMapView *)sender
annotationView:(MKAnnotationView *)aView
calloutAccessoryControlTapped:(UIControl *)control;</pre>
12. 使用一下代理方法来加载accessory views
<pre name="code" class="plain">-(void)mapView:(MKMapView *)sender didSelectAnnotationView:(MKAnnotationView *)aView
{
if ([aView.leftCalloutAccessoryView isKindOfClass:[UIImageView class]]) {
UIImageView *imageView = (UIImageView *)aView.leftCalloutAccessoryView;
imageView.image = ...; // if you do this in a GCD queue, be careful, views are reused!
}
}</pre>
13. 地图类型
<pre name="code" class="plain">@property MKMapType mapType;
<pre name="code" class="plain">enum {
MKMapTypeStandard = 0,
MKMapTypeSatellite,
MKMapTypeHybrid
};
typedef NSUInteger MKMapType; </pre>
<pre></pre>
<pre></pre>
14. 显示用户当前地址
<pre name="code" class="plain">@property BOOL showsUserLocation;
@property (readonly) BOOL isUserLocationVisible;
@property (readonly) MKUserLocation *userLocation;
MKUserLocation is an object which conforms to MKAnnotation which holds the user’s location.</pre>
15.限制用户对地图的操作
<pre name="code" class="plain">@property BOOL zoomEnabled;
@property BOOL scrollEnabled;</pre>
16. 控制地图的显示区域
<pre name="code" class="plain">@property MKCoordinateRegion region;
typedef struct {
CLLocationCoordinate2D center;
MKCoordinateSpan span;
} MKCoordinateRegion;
typedef struct {
CLLocationDegrees latitudeDelta;
CLLocationDegrees longitudeDelta;
}
- (void)setRegion:(MKCoordinateRegion)region animated:(BOOL)animated; // animate</pre>注意：
你赋给region属性的值通常不是最终保存的值，在设置显示区域的时候同时也设置了缩放等级。map view不能显示任意的缩放等级，因此map view会选择一个能够尽可能显示你指定区域大小的缩放等级，然后根据此时显示的区域来保存。
<pre name="code" class="plain">@property CLLocationCoordinate2D centerCoordinate;
- (void)setCenterCoordinate:(CLLocationCoordinate2D)center animated:(BOOL)animated;</pre>
17. 地图载入通知
<pre name="code" class="plain">Remember that the maps are downloaded from Google earth.
- (void)mapViewWillStartLoadingMap:(MKMapView *)sender;
- (void)mapViewDidFinishLoadingMap:(MKMapView *)sender;
- (void)mapViewDidFailLoadingMap:(MKMapView *)sender withError:(NSError *)error;</pre>
18.
</pre>