iOS位置服務過濾無效/不準確位置的方法

Question

我在一些應用程序中使用Location Services。我在我的locationManager:didUpdateToLocation:fromLocation:方法中使用了一種方法來過濾不良，不準確或太遠的位置。並儘量減少GPS「抖動」。這裏是我使用的：

/** 
* Check if we have a valid location 
* 
* @version $Revision: 0.1 
*/ 
+ (BOOL)isValidLocation:(CLLocation *)newLocation withOldLocation:(CLLocation *)oldLocation { 

    // Filter out nil locations 
    if (!newLocation) return NO; 

    // Filter out points by invalid accuracy 
    if (newLocation.horizontalAccuracy < 0) return NO; 
    if (newLocation.horizontalAccuracy > 66) return NO; 

    // Filter out points by invalid accuracy 
    #if !TARGET_IPHONE_SIMULATOR 
    if (newLocation.verticalAccuracy < 0) return NO; 
    #endif 

    // Filter out points that are out of order 
    NSTimeInterval secondsSinceLastPoint = [newLocation.timestamp timeIntervalSinceDate:oldLocation.timestamp]; 
    if (secondsSinceLastPoint < 0) return NO; 

    // Make sure the update is new not cached 
    NSTimeInterval locationAge = -[newLocation.timestamp timeIntervalSinceNow]; 
    if (locationAge > 5.0) return NO; 

    // Check to see if old and new are the same 
    if ((oldLocation.coordinate.latitude == newLocation.coordinate.latitude) && (oldLocation.coordinate.longitude == newLocation.coordinate.longitude)) 
     return NO; 

    return YES; 

}//end 

有沒有人有任何改善這種方法，使其更加準確？是過高的horizontalAccuracy會收到很多無效的位置？我應該降低這個嗎？

有沒有辦法讓iPhone上的gps「抖動」

Answer 1

除了這些還有一個我用：

if(self.lastKnownLocation) 
{ 
    CLLocationDistance dist = [newLocation distanceFromLocation:self.lastKnownLocation]; 

    if(dist > newLocation.horizontalAccuracy) 
    { 
      //..... 
    } 
} 

哪裏self.lastKnownLocation實際上是最後一個有效位置，我已經和它是一個：

@property(nonatomic, copy) CLLocation *lastKnownLocation; 

Answer 2

-(void)locationManager:(CLLocationManager *)manager 
    didUpdateToLocation:(CLLocation *)newLocation 
      fromLocation:(CLLocation *)oldLocation 
{ 
if (!newLocation) 
    { 
     NSLog(@"Filter out points by invalid accuracy"); 
     return; 
    } 

    // Filter out points by invalid accuracy 
    if (newLocation.horizontalAccuracy < 0) 
    { 
     return; 
    } 
    if(oldLocation.coordinate.latitude>90 && oldLocation.coordinate.latitude<-90 && oldLocation.coordinate.longitude>180 && oldLocation.coordinate.longitude<-180) 
    { 
     NSLog(@"old"); 
     return; 
    } 
    if(newLocation.coordinate.latitude>90 || newLocation.coordinate.latitude<-90 || newLocation.coordinate.longitude>180 || newLocation.coordinate.longitude<-180) 
    { 
     NSLog(@"new"); 
     return; 
    } 

    /////// 
    NSDate *eventDate=newLocation.timestamp; 
    NSTimeInterval eventinterval=[eventDate timeIntervalSinceNow]; 


    if (abs(eventinterval)<30.0) 
    {   
     if (newLocation.horizontalAccuracy>=0 && newLocation.horizontalAccuracy<20) 
     { 
      **//finally you are getting right updated value here....** 
     }   
    }   
} 

Answer 3

您可以檢出該

https://medium.com/@mizutori/make-it-even-better-than-nike-how-to-filter-locations-tracking-highly-accurate-location-in-774be045f8d6

的主要思想是，以文件服務器上的數據的方法didUpdateLocation:

過濾方法就是這樣的：

func filterAndAddLocation(_ location: CLLocation) -> Bool{ 
    let age = -location.timestamp.timeIntervalSinceNow 

    if age > 10{ 
     return false 
    } 

    if location.horizontalAccuracy < 0{ 
     return false 
    } 

    if location.horizontalAccuracy > 100{ 
     return false 
    } 

    locationDataArray.append(location) 

    return true 

}