從iOS應用中服務器上的文本文件中搜索經度和緯度范圍

Question

我正在嘗試在文本文件（可在url中找到）中搜索，有緯度，經度和其他信息，以逗號分隔。 我需要搜索最接近應用程序中用戶選擇的緯度的緯度。 代碼已完成，可以讀取該文件並進行搜索，但無法完美運行。 請讓我知道，在這種情況下我該如何處理。 1）文件實時更新，因此每次用戶選擇位置並單擊以獲取信息時，我都需要調用url並讀取文件。 2）然后搜索最接近用戶所選緯度的緯度。

NSDICTIONARY數據獲取：-

(
    {
    "altitude_m" = "90.0";
    engName = “Station 1”;
    grkName = "\U039d\U03ad\U03b1 \U039c\U03ac\U03ba\U03c1\U03b7 \U0391\U03c4\U03c4\U03b9\U03ba\U03ae\U03c2";
    "humidity_P" = "50.0";
    lat = "38.058873";
    "local_time" = "16:20";
    lon = "23.976741";
    "pressure_hPA" = "1019.9";
    "rain_mm" = "0.0";
    "tem_C" = "17.2";
    "wind_Gusts_khm" = "51.5";
    "wind_degrees" = "22.5";
    "wind_kmh" = "25.7";
}
{
    "altitude_m" = "90.0";
    engName = “Station 2”;
    grkName = "\U039d\U03ad\U03b1 \U039c\U03ac\U03ba\U03c1\U03b7 \U0391\U03c4\U03c4\U03b9\U03ba\U03ae\U03c2";
    "humidity_P" = "50.0";
    lat = "38.048873";
    "local_time" = "16:20";
    lon = "23.876741";
    "pressure_hPA" = "1019.9";
    "rain_mm" = "0.0";
    "tem_C" = "17.2";
    "wind_Gusts_khm" = "51.5";
    "wind_degrees" = "22.5";
    "wind_kmh" = "25.7";
}
{
    "altitude_m" = "90.0";
    engName = “Station 3”;
    grkName = "\U039d\U03ad\U03b1 \U039c\U03ac\U03ba\U03c1\U03b7 \U0391\U03c4\U03c4\U03b9\U03ba\U03ae\U03c2";
    "humidity_P" = "50.0";
    lat = "38.059873";
    "local_time" = "16:20";
    lon = "23.986741";
    "pressure_hPA" = "1019.9";
    "rain_mm" = "0.0";
    "tem_C" = "17.2";
    "wind_Gusts_khm" = "51.5";
    "wind_degrees" = "22.5";
    "wind_kmh" = "25.7";
}

//匹配功能：-

-(void)matchLAtLongNow: (NSString *)latitude :(NSString *)longitude {


CLLocationCoordinate2D pinlocation;

pinlocation.latitude   = [latitude doubleValue];

pinlocation.longitude  = [longitude doubleValue];


float minLat = pinlocation.latitude - (searchDistance / 69);

float maxLat = pinlocation.latitude + (searchDistance / 69);


float minLon = pinlocation.longitude - searchDistance / fabs(cos(deg2rad(pinlocation.latitude))*69);
float maxLon = pinlocation.longitude + searchDistance / fabs(cos(deg2rad(pinlocation.longitude))*69);

NSPredicate *predicate = [NSPredicate predicateWithFormat:
                          @"lat <= %f AND lat >= %f AND lon <= %f AND lon >= %f",
                          maxLat, minLat, maxLon, minLon];

MatchedTxtArray = [myArray filteredArrayUsingPredicate:applePred];


}

//得到錯誤*由於未捕獲的異常'NSInvalidArgumentException'而終止應用程序，原因：'-[__ NSCFNumber _fastCStringContents]：無法識別的選擇器發送到實例0x175426460'*第一個拋出調用棧：

Answer 1

NSDictionaries返回NSNumbers。 檢查您在哪里調用matchAtLongNow：您可能在期望字符串的地方有NSNumbers。

Answer 2

聽起來您需要地理搜索，而不是將其包含在某些閾值內。 我會改寫成這樣的東西：

NSArray *objects; // this is your parsed file, an array of dictionaries
CLLocation *userLocation;  // this is your user location

// sort the dictionary in order of distance to the userLocation
NSArray *sortedObjects = [objects sortedArrayUsingComparator:^(NSDictionary *objA,NSDictionary *objB) {
    CLLocationDistance distanceA = [self distanceToObject:objA from:userLocation];
    CLLocationDistance distanceB = [self distanceToObject:objB from:userLocation];
    return (NSComparisonResult)(distanceB-distanceA);
}];

sortedObjects將包含從userLocation到從最遠到最遠的字典排序。我們只需要一個函數即可產生字典中經緯度值到userLocation的距離...

- (CLLocationDistance)distanceToObject:(NSDictionary *)object from:(CLLocation *)location {
    CLLocationDegrees latitude = [object[@"lat"] doubleValue];
    CLLocationDegrees longitude = [object[@"lob"] doubleValue];
    CLLocation *objectLocation = [[CLLocation alloc] initWithLatitude:latitude longitude:longitude];
    return [objectLocation distanceFromLocation:location];
}