iOS Location service 定位服務

取得所在位置是行動裝置的一大特色，在地化、導航、語言、文化都跟這服務脫離不了關係，在iOS中使用這服務需要先import一個framework如下

CoreLocation.framework

加入framework後還必須加入CoreLocation的Delegate，以及因為下面範例中使用者如果將定位服務關閉彈出Alert詢問使用者是否將開啟定位服務，需要加入的Delegate如下(在.h檔中)

CLLocationManagerDelegate, UIAlertViewDelegate

加入後應該會看到錯誤，因為CoreLocation這framework還沒被import，必須在.h檔上方先import這行

#import <CoreLocation/CoreLocation.h>

使用的方式如下(.m檔)

//初始化LocationService
-(void) openLocationService{
//location
CLLocationManager *locationManager = [[CLLocationManager alloc] init];
locationManager.delegate = self;
locationManager.distanceFilter = kCLDistanceFilterNone; // whenever we move
locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters; // 100 m
[locationManager startUpdatingLocation];
}

//給地址、經緯度後直接開啟Google map導航
-(void)navivationToTheAddress:(NSString *)address myLatitude:(double)latitude myLongitude:(double)longitude{
NSString* urlString = [NSString stringWithFormat:@"http://maps.google.com/maps?f=d&source=s_d&saddr=%f,%f&daddr=%@", latitude, longitude, address];
NSString *escaped = [urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:escaped]];
}

//location Delegate
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation{
NSString *address = [self.myWebView stringByEvaluatingJavaScriptFromString:@"naviAddress"];
[self navivationToTheAddress:address myLatitude:manager.location.coordinate.latitude myLongitude:manager.location.coordinate.longitude];

[manager stopUpdatingLocation];
}

//錯誤發生時回報方式
-(void) locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error{
//NSLog(@"didFailWithError = %@", error);
NSString *errorString;
[manager stopUpdatingLocation];
NSLog(@"Error: %@",[error localizedDescription]);
switch([error code]) {
case kCLErrorDenied:
errorString = @"您已關閉定位服務無法順利導航，是否立即開啟服務？";
break;
case kCLErrorLocationUnknown:
errorString = @"無法順利取得您的位置";
break;
default:
errorString = @"無法順利取得您的位置";
break;
}

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Golf球場指南" message:errorString delegate:self cancelButtonTitle:@"收後啟用" otherButtonTitles:@"立即啟用", nil];
[alert show];
}

-(void) alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{
NSLog(@"clickedButtonAtIndex buttonIndex = %d", buttonIndex);
if(buttonIndex == 1){
//點選"立即開啟"後打開設定中的定位服務開啟畫面
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"prefs:root=LOCATION_SERVICES"]];
}
}

相關連結
iOS Developer Library
iOS Developer Library - CoreLocation Framework