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移動経路を記録し、後で取得できるように保存する iOS アプリケーションを作成しています。パスを描画するためのコードのほとんどは、サンプル コードBreadcrumbに基づいています。

今、描画されたオーバーレイを保存する機能を追加しています。それを行う最良の方法は何ですか？使用できますCoreDataが、後で再度取得するのではなく、描画されたオーバーレイに対して多くのことを行うつもりはありません。私は現在、単純なNSArray. CrumbPath オブジェクトを変換NSDataして配列に格納します。後でそれを取得し、CrumbPath に変換します。しかし、私は何か間違ったことをしているようです。

@interface CrumbPath : NSObject <MKOverlay>
{
    MKMapPoint *points;
    NSUInteger pointCount;
    NSUInteger pointSpace;

    MKMapRect boundingMapRect;

    pthread_rwlock_t rwLock;
}

- (id)initWithCenterCoordinate:(CLLocationCoordinate2D)coord;
- (MKMapRect)addCoordinate:(CLLocationCoordinate2D)coord;

@property (readonly) MKMapPoint *points;
@property (readonly) NSUInteger pointCount;

@end

次のように CrumbPath オブジェクト「クラム」を保存します。

NSData *pointData = [NSData dataWithBytes:crumbs.points length:crumbs.pointCount * sizeof(MKMapPoint)];
[patternArray addObject:pointData];
[timeArray addObject:date];

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
// Create the full file path by appending the desired file name
NSString *patternFile = [documentsDirectory stringByAppendingPathComponent:@"patterns.dat"];
NSString *timeFile = [documentsDirectory stringByAppendingPathComponent:@"times.dat"];

//Save the array
[patternArray writeToFile:patternFile atomically:YES];
[timeArray writeToFile:timeFile atomically:YES];

そして、後で次のように取得して、表に表示します。

NSData *pointData = [appDelegate.patternArray objectAtIndex:indexPath.row];
MKMapPoint *points = malloc(pointData.length);
(void)memcpy([pointData bytes], points, sizeof(pointData));

そして、パスを再度構築します。

crumbs = [[CrumbPath alloc] initWithCenterCoordinate:MKCoordinateForMapPoint(points[0])];
for (int i = 1; i <= pointCount; i++) {
    [crumbs addCoordinate:MKCoordinateForMapPoint(points[i])];
}    
[map addOverlay:crumbs];

ただし、エラーが発生します。'NSInvalidArgumentException', reason: '-[NSConcreteData isEqualToString:]: unrecognized selector sent to instance

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1 に答える 1

2

Personally, I'd be inclined to do it as follows:

  1. First, I'd be inclined to save the C array of CLLocationCoordinate2D coordinates that I pass to MKPolygon instance method polygonWithCoordinates (rather than a MKMapPoint C array). You can adapt this code if you'd rather use MKMapPoints, but I prefer a format which I can examine externally and make sense of (namely the latitude and longitude values of CLLocationCoordinate2D). So, let's assume that you make your MKPolygon with a line of code like so:

    MKPolygon* poly = [MKPolygon polygonWithCoordinates:coordinates count:count];

    You could, therefore save the coordinates like so:

    [self writeCoordinates:coordinates count:count file:filename];

    Where writeCoordinates:count:filename: is defined as follows:

    - (void)writeCoordinates:(CLLocationCoordinate2D *)coordinates count:(NSUInteger)count file:(NSString *)filename
{
    NSData *data = [NSData dataWithBytes:coordinates length:count * sizeof(CLLocationCoordinate2D)];
    [data writeToFile:filename atomically:NO];
}

    You could then make the MKPolygon from the file with:

    MKPolygon* poly = [self polygonWithContentsOfFile:filename];

    where polygonWithContentsOfFile is defined as:

    - (MKPolygon *)polygonWithContentsOfFile:(NSString *)filename
{
    NSData *data = [NSData dataWithContentsOfFile:filename];
    NSUInteger count = data.length / sizeof(CLLocationCoordinate2D);
    CLLocationCoordinate2D *coordinates = (CLLocationCoordinate2D *)data.bytes;

    return [MKPolygon polygonWithCoordinates:coordinates count:count];
}

  2. Alternatively, you could read and write the array of CLLocationCoordinate2D in a plist format (which renders it in a human readable format), by replacing the two above methods with:

    const NSString *kLatitudeKey = @"latitude";
const NSString *kLongitudeKey = @"longitude";

- (void)writeCoordinates:(CLLocationCoordinate2D *)coordinates count:(NSUInteger)count file:(NSString *)filename
{
    NSMutableArray *array = [NSMutableArray arrayWithCapacity:count];

    for (NSUInteger i = 0; i < count; i++)
    {
        CLLocationCoordinate2D coordinate = coordinates[i];
        [array addObject:@{kLatitudeKey:@(coordinate.latitude), kLongitudeKey:@(coordinate.longitude)}];
    }

    [array writeToFile:filename atomically:NO];
}

- (MKPolygon *)polygonWithContentsOfFile:(NSString *)filename
{        
    NSArray *array = [NSArray arrayWithContentsOfFile:filename];
    NSUInteger count = [array count];
    CLLocationCoordinate2D coordinates[count];

    for (NSUInteger i = 0; i < count; i++)
    {
        NSDictionary *dictionary = array[i];
        coordinates[i].latitude = [dictionary[kLatitudeKey] doubleValue];
        coordinates[i].longitude = [dictionary[kLongitudeKey] doubleValue];
    }

    return [MKPolygon polygonWithCoordinates:coordinates count:count];
}

Clearly you'd want to add error checking code to make sure that the writeToFile and the dataWithContentsOfFile (or arrayWithContentsOfFile) succeeded, but hopefully this gives you the idea.

于 2013-03-01T03:36:13.000 に答える