我想在地图上绘制与我通过 Google Directions API 获取的方向 JSON 相对应的路线：https://developers.google.com/maps/documentation/directions/start
我已经弄清楚如何从步骤字段中提取纬度和经度，但这并不能很好地遵循弯曲的道路。我认为我需要的是解码折线信息，我找到了谷歌关于如何编码折线的说明：https://developers.google.com/maps/documentation/utilities/polylinealgorithm
我确实在这里找到了一些适用于 Android 的代码以及解码折线的 Javascript，例如：
使用 google Directions API 绘制地图视图绘制方向 - 解码折线
但是我找不到相同的 Objective-C iPhone 代码，有人可以帮我吗？我确信如果有必要的话我可以自己做，但如果它已经在某个地方可用，它肯定会节省我一些时间。
编辑：这里的关键是能够逐个字符地解码 Base64 编码。更具体地说，我从 Google 得到了类似 JSON 的内容，它是使用 base64 编码等进行编码的：
... "overview_polyline" : {
"points" : "ydelDz~vpN_@NO@QEKWIYIIO?YCS@WFGBEBICCAE?G@y@RKBEBEBAD?HTpB@LALALCNEJEFSP_@LyDv@aB\\GBMB"
},
...
注意：我应该提到这个问题是指 Google Maps API v1，在 v2 中使用 GMSPolyLine polyLineWithPath 更容易做到这一点，下面的许多答案都会告诉你（感谢 @cdescours）。
我希望链接到我自己的博客文章（如果它与问题相关）不违反规则，但我过去已经解决了这个问题。来自链接帖子的独立答案：
@implementation MKPolyline (MKPolyline_EncodedString)
+ (MKPolyline *)polylineWithEncodedString:(NSString *)encodedString {
const char *bytes = [encodedString UTF8String];
NSUInteger length = [encodedString lengthOfBytesUsingEncoding:NSUTF8StringEncoding];
NSUInteger idx = 0;
NSUInteger count = length / 4;
CLLocationCoordinate2D *coords = calloc(count, sizeof(CLLocationCoordinate2D));
NSUInteger coordIdx = 0;
float latitude = 0;
float longitude = 0;
while (idx < length) {
char byte = 0;
int res = 0;
char shift = 0;
do {
byte = bytes[idx++] - 63;
res |= (byte & 0x1F) << shift;
shift += 5;
} while (byte >= 0x20);
float deltaLat = ((res & 1) ? ~(res >> 1) : (res >> 1));
latitude += deltaLat;
shift = 0;
res = 0;
do {
byte = bytes[idx++] - 0x3F;
res |= (byte & 0x1F) << shift;
shift += 5;
} while (byte >= 0x20);
float deltaLon = ((res & 1) ? ~(res >> 1) : (res >> 1));
longitude += deltaLon;
float finalLat = latitude * 1E-5;
float finalLon = longitude * 1E-5;
CLLocationCoordinate2D coord = CLLocationCoordinate2DMake(finalLat, finalLon);
coords[coordIdx++] = coord;
if (coordIdx == count) {
NSUInteger newCount = count + 10;
coords = realloc(coords, newCount * sizeof(CLLocationCoordinate2D));
count = newCount;
}
}
MKPolyline *polyline = [MKPolyline polylineWithCoordinates:coords count:coordIdx];
free(coords);
return polyline;
}
@end
最好、最简单的答案应该是使用框架中Google提供的方法：
[GMSPolyline polylineWithPath:[GMSPath pathFromEncodedPath:encodedPath]]如果您在 iOS 上使用 Google 地图并想要绘制包括折线在内的路线，谷歌本身提供了一种更简单的方法来从折线获取 GMSPath，
GMSPath *pathFromPolyline = [GMSPath pathFromEncodedPath:polyLinePoints];
完整代码如下：
+ (void)callGoogleServiceToGetRouteDataFromSource:(CLLocation *)sourceLocation toDestination:(CLLocation *)destinationLocation onMap:(GMSMapView *)mapView_{
NSString *baseUrl = [NSString stringWithFormat:@"http://maps.googleapis.com/maps/api/directions/json?origin=%f,%f&destination=%f,%f&sensor=false", sourceLocation.coordinate.latitude, sourceLocation.coordinate.longitude, destinationLocation.coordinate.latitude, destinationLocation.coordinate.longitude];
NSURL *url = [NSURL URLWithString:[baseUrl stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
NSLog(@"Url: %@", url);
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
GMSMutablePath *path = [GMSMutablePath path];
NSError *error = nil;
NSDictionary *result = [NSJSONSerialization JSONObjectWithData:data options:0 error:&error];
NSArray *routes = [result objectForKey:@"routes"];
NSDictionary *firstRoute = [routes objectAtIndex:0];
NSDictionary *leg = [[firstRoute objectForKey:@"legs"] objectAtIndex:0];
NSArray *steps = [leg objectForKey:@"steps"];
int stepIndex = 0;
CLLocationCoordinate2D stepCoordinates[1 + [steps count] + 1];
for (NSDictionary *step in steps) {
NSDictionary *start_location = [step objectForKey:@"start_location"];
stepCoordinates[++stepIndex] = [self coordinateWithLocation:start_location];
[path addCoordinate:[self coordinateWithLocation:start_location]];
NSString *polyLinePoints = [[step objectForKey:@"polyline"] objectForKey:@"points"];
GMSPath *polyLinePath = [GMSPath pathFromEncodedPath:polyLinePoints];
for (int p=0; p<polyLinePath.count; p++) {
[path addCoordinate:[polyLinePath coordinateAtIndex:p]];
}
if ([steps count] == stepIndex){
NSDictionary *end_location = [step objectForKey:@"end_location"];
stepCoordinates[++stepIndex] = [self coordinateWithLocation:end_location];
[path addCoordinate:[self coordinateWithLocation:end_location]];
}
}
GMSPolyline *polyline = nil;
polyline = [GMSPolyline polylineWithPath:path];
polyline.strokeColor = [UIColor grayColor];
polyline.strokeWidth = 3.f;
polyline.map = mapView_;
}];
}
+ (CLLocationCoordinate2D)coordinateWithLocation:(NSDictionary*)location
{
double latitude = [[location objectForKey:@"lat"] doubleValue];
double longitude = [[location objectForKey:@"lng"] doubleValue];
return CLLocationCoordinate2DMake(latitude, longitude);
}
斯威夫特3.0
let polyline = GMSPolyline(path: GMSPath.init(fromEncodedPath: encodedPolyline))
这不是 Objective-C 中的内容，但如果您想从 Google 地图中解码折线字符串，Google 就会向您提供此线程。如果其他人需要它（就像我一样），这里有一个用于解码折线字符串的 Python 实现。这是从 Mapbox JavaScript 版本移植的；在我的 repo 页面上可以找到更多信息。
def decode_polyline(polyline_str):
index, lat, lng = 0, 0, 0
coordinates = []
changes = {'latitude': 0, 'longitude': 0}
# Coordinates have variable length when encoded, so just keep
# track of whether we've hit the end of the string. In each
# while loop iteration, a single coordinate is decoded.
while index < len(polyline_str):
# Gather lat/lon changes, store them in a dictionary to apply them later
for unit in ['latitude', 'longitude']:
shift, result = 0, 0
while True:
byte = ord(polyline_str[index]) - 63
index+=1
result |= (byte & 0x1f) << shift
shift += 5
if not byte >= 0x20:
break
if (result & 1):
changes[unit] = ~(result >> 1)
else:
changes[unit] = (result >> 1)
lat += changes['latitude']
lng += changes['longitude']
coordinates.append((lat / 100000.0, lng / 100000.0))
return coordinates
- (MKPolyline *)polylineWithEncodedString:(NSString *)encodedString {
const char *bytes = [encodedString UTF8String];
NSUInteger length = [encodedString lengthOfBytesUsingEncoding:NSUTF8StringEncoding];
NSUInteger idx = 0;
NSUInteger count = length / 4;
CLLocationCoordinate2D *coords = calloc(count, sizeof(CLLocationCoordinate2D));
NSUInteger coordIdx = 0;
float latitude = 0;
float longitude = 0;
while (idx < length) {
char byte = 0;
int res = 0;
char shift = 0;
do {
byte = bytes[idx++] - 63;
res |= (byte & 0x1F) << shift;
shift += 5;
} while (byte >= 0x20);
float deltaLat = ((res & 1) ? ~(res >> 1) : (res >> 1));
latitude += deltaLat;
shift = 0;
res = 0;
do {
byte = bytes[idx++] - 0x3F;
res |= (byte & 0x1F) << shift;
shift += 5;
} while (byte >= 0x20);
float deltaLon = ((res & 1) ? ~(res >> 1) : (res >> 1));
longitude += deltaLon;
float finalLat = latitude * 1E-5;
float finalLon = longitude * 1E-5;
CLLocationCoordinate2D coord = CLLocationCoordinate2DMake(finalLat, finalLon);
coords[coordIdx++] = coord;
if (coordIdx == count) {
NSUInteger newCount = count + 10;
coords = realloc(coords, newCount * sizeof(CLLocationCoordinate2D));
count = newCount;
}
}
MKPolyline *polyline = [MKPolyline polylineWithCoordinates:coords count:coordIdx];
free(coords);
return polyline;
}
- (MKPolygonRenderer *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay {
// MKPolygonRenderer *polylineView = [[MKPolygonRenderer alloc] initWithOverlay:overlay];
MKPolylineView *polylineView = [[MKPolylineView alloc] initWithPolyline:overlay];
polylineView.strokeColor = [UIColor redColor];
polylineView.lineWidth = 4.0;
[self zoomToPolyLine:mapview polyline:overlay animated:YES];
return polylineView;
}
-(void)zoomToPolyLine: (MKMapView*)map polyline: (MKPolyline*)polyline animated: (BOOL)animated
{
[map setVisibleMapRect:[polyline boundingMapRect] edgePadding:UIEdgeInsetsMake(25.0, 25.0, 25.0, 25.0) animated:animated];
}
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
// NSLog(@"didUpdateToLocation: %@", newLocation);
CLLocation *currentLocation = newLocation;
if (currentLocation != nil) {
currlong = [NSString stringWithFormat:@"%.8f", currentLocation.coordinate.longitude];
currlt = [NSString stringWithFormat:@"%.8f", currentLocation.coordinate.latitude];
}
NSString *origin = [NSString stringWithFormat:@"%@%@%@",currlt,@",",currlong];
//I have just mention static location
NSString *drivein = @"23.0472963,72.52757040000006";
NSString *apikey = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/directions/json?origin=%@&destination=%@",origin,drivein];
NSURL *url = [NSURL URLWithString:apikey];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
NSURLResponse *response;
NSError *error;
NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
if(!error)
{
NSData *data = [responseString dataUsingEncoding:NSUTF8StringEncoding];
NSDictionary *jsonResponse = [NSJSONSerialization JSONObjectWithData:data
options:kNilOptions
error:&error];
NSArray *routesArray = [jsonResponse objectForKey:@"routes"];
NSLog(@"route array %@",routesArray);
if ([routesArray count] > 0)
{
NSDictionary *routeDict = [routesArray objectAtIndex:0];
NSDictionary *routeOverviewPolyline = [routeDict objectForKey:@"overview_polyline"];
NSString *points = [routeOverviewPolyline objectForKey:@"points"];
MKPolyline *line = [self polylineWithEncodedString:points];
[mapview addOverlay:line];
}
}
MKCoordinateRegion viewRegion = MKCoordinateRegionMakeWithDistance(currentLocation.coordinate, 500, 500);
MKCoordinateRegion adjustedRegion = [mapview regionThatFits:viewRegion];
[mapview setRegion:adjustedRegion animated:YES];
mapview.showsUserLocation = YES;
MKPointAnnotation *point = [[MKPointAnnotation alloc] init];
point.coordinate = currentLocation.coordinate;
point.title = @"Your current Locations";
point.subtitle = @"You are here!";
[mapview addAnnotation:point];
[locationmanger stopUpdatingLocation];
}
这是我在路线应用程序中的操作方法。 keyPlace 是您的目标对象
- (void)getDirections {
CLLocation *newLocation;// = currentUserLocation;
MKPointAnnotation *annotation = [[[MKPointAnnotation alloc] init] autorelease];
annotation.coordinate = CLLocationCoordinate2DMake(newLocation.coordinate.latitude, newLocation.coordinate.longitude);
annotation.title = @"You";
[mapView addAnnotation:annotation];
CLLocationCoordinate2D endCoordinate;
NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/directions/json?origin=%f,%f&destination=%f,%f&sensor=false&mode=walking", newLocation.coordinate.latitude, newLocation.coordinate.longitude, keyPlace.lat, keyPlace.lon]];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request startSynchronous];
if ([[request.responseString.JSONValue valueForKey:@"status"] isEqualToString:@"ZERO_RESULTS"]) {
[[[[UIAlertView alloc] initWithTitle:@"Error"
message:@"Could not route path from your current location"
delegate:nil
cancelButtonTitle:@"Close"
otherButtonTitles:nil, nil] autorelease] show];
self.navigationController.navigationBar.userInteractionEnabled = YES;
return;
}
int points_count = 0;
if ([[request.responseString.JSONValue objectForKey:@"routes"] count])
points_count = [[[[[[request.responseString.JSONValue objectForKey:@"routes"] objectAtIndex:0] objectForKey:@"legs"] objectAtIndex:0] objectForKey:@"steps"] count];
if (!points_count) {
[[[[UIAlertView alloc] initWithTitle:@"Error"
message:@"Could not route path from your current location"
delegate:nil
cancelButtonTitle:@"Close"
otherButtonTitles:nil, nil] autorelease] show];
self.navigationController.navigationBar.userInteractionEnabled = YES;
return;
}
CLLocationCoordinate2D points[points_count * 2];
int j = 0;
NSArray *steps = nil;
if (points_count && [[[[request.responseString.JSONValue objectForKey:@"routes"] objectAtIndex:0] objectForKey:@"legs"] count])
steps = [[[[[request.responseString.JSONValue objectForKey:@"routes"] objectAtIndex:0] objectForKey:@"legs"] objectAtIndex:0] objectForKey:@"steps"];
for (int i = 0; i < points_count; i++) {
double st_lat = [[[[steps objectAtIndex:i] objectForKey:@"start_location"] valueForKey:@"lat"] doubleValue];
double st_lon = [[[[steps objectAtIndex:i] objectForKey:@"start_location"] valueForKey:@"lng"] doubleValue];
//NSLog(@"lat lon: %f %f", st_lat, st_lon);
if (st_lat > 0.0f && st_lon > 0.0f) {
points[j] = CLLocationCoordinate2DMake(st_lat, st_lon);
j++;
}
double end_lat = [[[[steps objectAtIndex:i] objectForKey:@"end_location"] valueForKey:@"lat"] doubleValue];
double end_lon = [[[[steps objectAtIndex:i] objectForKey:@"end_location"] valueForKey:@"lng"] doubleValue];
if (end_lat > 0.0f && end_lon > 0.0f) {
points[j] = CLLocationCoordinate2DMake(end_lat, end_lon);
endCoordinate = CLLocationCoordinate2DMake(end_lat, end_lon);
j++;
}
}
MKPolyline *polyline = [MKPolyline polylineWithCoordinates:points count:points_count * 2];
[mapView addOverlay:polyline];
}
#pragma mark - MapKit
- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation {
MKPinAnnotationView *annView = [[[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:@"currentloc"] autorelease];
annView.canShowCallout = YES;
annView.animatesDrop = YES;
return annView;
}
- (MKOverlayView *)mapView:(MKMapView *)mapView
viewForOverlay:(id<MKOverlay>)overlay {
MKPolylineView *overlayView = [[[MKPolylineView alloc] initWithOverlay:overlay] autorelease];
overlayView.lineWidth = 5;
overlayView.strokeColor = [UIColor purpleColor];
overlayView.fillColor = [[UIColor purpleColor] colorWithAlphaComponent:0.5f];
return overlayView;
}
如果有人需要 VBA 中的解码代码，这里有一个（工作）端口：
Function decodeGeopoints(encoded)
decodeGeopoints = ""
' This code is a port to VBA from code published here:
' http://blog.synyx.de/2010/06/routing-driving-directions-on-android-part-1-get-the-route/
'//decoding
'List poly = new ArrayList();
'// replace two backslashes by one (some error from the transmission)
'encoded = encoded.replace("\\", "\");
encoded = Replace(encoded, "\\", "\")
'int index = 0, len = encoded.length();
Dim index As Long
index = 0
Dim leng As Long
leng = Len(encoded)
'int lat = 0, lng = 0;
Dim lat As Long
lat = 0
Dim lng As Long
lng = 0
'while (index < len) {
While (index < leng)
'int b, shift = 0, result = 0;
Dim b, shift, result As Long
b = 0
shift = 0
result = 0
'do {
Do
'b = encoded.charAt(index++) - 63;
index = index + 1
b = Asc(Mid(encoded, index, 1)) - 63
'result |= (b & 0x1f) << shift;
result = result Or ((b And 31) * (2 ^ shift))
'shift += 5;
shift = shift + 5
'} while (b >= 0x20);
Loop While (b >= 32)
'int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
Dim dlat As Long
If (result And 1) <> 0 Then
dlat = Not Int(result / 2)
Else
dlat = Int(result / 2)
End If
'lat += dlat;
lat = lat + dlat
'shift = 0;
shift = 0
'result = 0;
result = 0
'do {
Do
'b = encoded.charAt(index++) - 63;
index = index + 1
b = Asc(Mid(encoded, index, 1)) - 63
'result |= (b & 0x1f) << shift;
result = result Or ((b And 31) * (2 ^ shift))
'shift += 5;
shift = shift + 5
'} while (b >= 0x20);
Loop While (b >= 32)
'int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
Dim dlng As Long
If (result And 1) <> 0 Then
dlng = Not Int(result / 2)
Else
dlng = Int(result / 2)
End If
'lng += dlng;
lng = lng + dlng
'GeoPoint p = new GeoPoint((int) (((double) lat / 1E5) * 1E6), (int) (((double) lng / 1E5) * 1E6));
Dim myLat, myLng As Double
myLat = (lat / 100000)
'myLat = myLat * 1000000
myLng = (lng / 100000)
'myLng = myLng * 1000000
'poly.add(p);
decodeGeopoints = decodeGeopoints & Comma2Dot(myLng) & "," & Comma2Dot(myLat) & ",0 "
'}
Wend
End Function
对于谷歌地图，它已经有一个直接的方法，
polylineWithPath-(void)drawPathFrom:(CLLocation*)source toDestination:(CLLocation*)destination{
NSString *baseUrl = [NSString stringWithFormat:@"http://maps.googleapis.com/maps/api/directions/json?origin=%f,%f&destination=%f,%f&sensor=true", source.coordinate.latitude, source.coordinate.longitude, destination.coordinate.latitude, destination.coordinate.longitude];
NSURL *url = [NSURL URLWithString:[baseUrl stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
NSLog(@"Url: %@", url);
NSURLRequest *request = [NSURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
if(!connectionError){
NSDictionary *result = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
NSArray *routes = [result objectForKey:@"routes"];
NSDictionary *firstRoute = [routes objectAtIndex:0];
NSString *encodedPath = [firstRoute[@"overview_polyline"] objectForKey:@"points"];
GMSPolyline *polyPath = [GMSPolyline polylineWithPath:[GMSPath pathFromEncodedPath:encodedPath]];
polyPath.strokeColor = [UIColor redColor];
polyPath.strokeWidth = 3.5f;
polyPath.map = _mapView;
}
}];
}
斯威夫特 4.2 / 斯威夫特 5
let gmsPolyline = GMSPolyline(path: GMSPath(fromEncodedPath: encodedPolyline))
gmsPolyline.map = map
这是我自己对 Sedate Alien 的答案的重新审视。 它是相同的实现，只是删除重复的代码并使用 NSMutableData 而不是手动分配东西。
@implementation MKPolyline (EncodedString)
+ (float)decodeBytes:(const char *)bytes atPos:(NSUInteger *)idx toValue:(float *)value {
char byte = 0;
int res = 0;
char shift = 0;
do {
byte = bytes[(*idx)++] - 0x3F;
res |= (byte & 0x1F) << shift;
shift += 5;
}
while (byte >= 0x20);
(*value) += ((res & 1) ? ~(res >> 1) : (res >> 1));
return (*value) * 1E-5;
}
+ (MKPolyline *)polylineWithEncodedString:(NSString *)encodedString {
const char *bytes = [encodedString UTF8String];
NSUInteger length = [encodedString lengthOfBytesUsingEncoding:NSUTF8StringEncoding];
NSUInteger idx = 0;
NSMutableData *data = [NSMutableData data];
float lat = 0;
float lon = 0;
CLLocationCoordinate2D coords = CLLocationCoordinate2DMake(0, 0);
while (idx < length) {
coords.latitude = [self decodeBytes:bytes atPos:&idx toValue:&lat];
coords.longitude = [self decodeBytes:bytes atPos:&idx toValue:&lon];
[data appendBytes:&coords length:sizeof(CLLocationCoordinate2D)];
}
return [MKPolyline polylineWithCoordinates:(CLLocationCoordinate2D *)data.bytes count:data.length / sizeof(CLLocationCoordinate2D)];
}
@end
这里的其他答案似乎是关于使用苹果地图，为了使用谷歌地图，我发现我必须对@SedateAlien的伟大类别进行一些修改。
修改类别
+ (GMSPolyline *)polylineWithEncodedString:(NSString *)encodedString {
const char *bytes = [encodedString UTF8String];
NSUInteger length = [encodedString lengthOfBytesUsingEncoding:NSUTF8StringEncoding];
NSUInteger idx = 0;
NSUInteger count = length / 4;
CLLocationCoordinate2D *coords = calloc(count, sizeof(CLLocationCoordinate2D));
NSUInteger coordIdx = 0;
float latitude = 0;
float longitude = 0;
while (idx < length) {
char byte = 0;
int res = 0;
char shift = 0;
do {
byte = bytes[idx++] - 63;
res |= (byte & 0x1F) << shift;
shift += 5;
} while (byte >= 0x20);
float deltaLat = ((res & 1) ? ~(res >> 1) : (res >> 1));
latitude += deltaLat;
shift = 0;
res = 0;
do {
byte = bytes[idx++] - 0x3F;
res |= (byte & 0x1F) << shift;
shift += 5;
} while (byte >= 0x20);
float deltaLon = ((res & 1) ? ~(res >> 1) : (res >> 1));
longitude += deltaLon;
float finalLat = latitude * 1E-5;
float finalLon = longitude * 1E-5;
CLLocationCoordinate2D coord = CLLocationCoordinate2DMake(finalLat, finalLon);
coords[coordIdx++] = coord;
if (coordIdx == count) {
NSUInteger newCount = count + 10;
coords = realloc(coords, newCount * sizeof(CLLocationCoordinate2D));
count = newCount;
}
}
GMSMutablePath *path = [[GMSMutablePath alloc] init];
int i;
for (i = 0; i < coordIdx; i++)
{
[path addCoordinate:coords[i]];
}
GMSPolyline *polyline = [GMSPolyline polylineWithPath:path];
free(coords);
return polyline;
}
使用
// Here I make the call to the Google Maps API to get the routes between two points...
....
// Get the encoded array of points.
NSString *points = routes[@"routes"][0][@"overview_polyline"][@"points"];
// Use the modified category to get a polyline from the points.
GMSPolyline *polyline = [GMSPolyline polylineWithEncodedString:points];
// Add the polyline to the map.
polyline.strokeColor = [UIColor redColor];
polyline.strokeWidth = 10.f;
polyline.map = theMapView;
}
如果其他人尝试在 swift 中执行此操作，这里是 @RootCode 的答案，适用于 swift (2.3)：
let path = GMSMutablePath()
let steps = directionsToShowOnMap.steps
for (idx, step) in steps.enumerate() {
path.addCoordinate(coordinateFromJson(step["start_location"]))
if let polylinePoints = step["polyline"].string, subpath = GMSPath(fromEncodedPath: polylinePoints) {
for c in 0 ..< subpath.count() {
path.addCoordinate(subpath.coordinateAtIndex(c))
}
}
if idx == steps.count - 1 {
path.addCoordinate(coordinateFromJson(step["end_location"]))
}
}
let polyline = GMSPolyline(path: path)
polyline.strokeColor = UIColor.blueColor()
polyline.strokeWidth = 3
polyline.map = mapView
然后：
private func coordinateFromJson(location: JSON) -> CLLocationCoordinate2D {
return CLLocationCoordinate2DMake(location["lat"].double!, location["lng"].double!)
}
我想分享 ChatGPT 版本的解决方案
public static List<Tuple<double, double>> DecodePolyline(string encodedPolyline)
{
List<Tuple<double, double>> polyLinePoints = new List<Tuple<double, double>>();
int index = 0;
int latitude = 0;
int longitude = 0;
while (index < encodedPolyline.Length)
{
int shift = 0;
int result = 0;
int currentByte;
do
{
currentByte = encodedPolyline[index++] - 63;
result |= (currentByte & 0x1F) << shift;
shift += 5;
}
while (currentByte >= 0x20);
int deltaLatitude = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
latitude += deltaLatitude;
shift = 0;
result = 0;
do
{
currentByte = encodedPolyline[index++] - 63;
result |= (currentByte & 0x1F) << shift;
shift += 5;
}
while (currentByte >= 0x20);
int deltaLongitude = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
longitude += deltaLongitude;
double finalLat = latitude / 1E5;
double finalLng = longitude / 1E5;
polyLinePoints.Add(new Tuple<double, double>(finalLat, finalLng));
}
return polyLinePoints;
}
经过尝试和测试
points: ec`xA_`saVAkC?o@?c@?O?}B?Q?K@qAAsB?e@Fe@Ae@?U?a@@G@E^gA
已解码
Latitude: 14.58755, Longitude: 121.01648
Latitude: 14.58756, Longitude: 121.01718
Latitude: 14.58756, Longitude: 121.01742
Latitude: 14.58756, Longitude: 121.0176
Latitude: 14.58756, Longitude: 121.01768
Latitude: 14.58756, Longitude: 121.01831
Latitude: 14.58756, Longitude: 121.0184
Latitude: 14.58756, Longitude: 121.01846
Latitude: 14.58755, Longitude: 121.01887
Latitude: 14.58756, Longitude: 121.01945
Latitude: 14.58756, Longitude: 121.01964
Latitude: 14.58752, Longitude: 121.01983
Latitude: 14.58753, Longitude: 121.02002
Latitude: 14.58753, Longitude: 121.02013
Latitude: 14.58753, Longitude: 121.0203
Latitude: 14.58752, Longitude: 121.02034
Latitude: 14.58751, Longitude: 121.02037
Latitude: 14.58735, Longitude: 121.02073
您也可以在这里验证 https://developers.google.com/maps/documentation/utilities/polylineutility