iOS GoogleMap 路径规划 Directions

谷歌给的api：
https://maps.googleapis.com/maps/api/directions/json?origin=39.99,116.31&destination=39.99,116.41&sensor=false&mode=walking

origin=起点经纬度 destination=终点经纬度
然后用请求一下：

• (void)getLine{
  NSString *url = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/directions/json?origin=%f,%f&destination=%f,%f&sensor=false&mode=walking&language=en",_coor.latitude,_coor.longitude,_lat,_lng];
  NSURLSessionDataTask *task = [[NSURLSession sharedSession] dataTaskWithURL:[NSURL URLWithString:url] completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
  if (!data) {
  return ;
  }
  NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
  if (error) {
  return;
  }
  dispatch_async(dispatch_get_main_queue(), ^{
  [self configWithData:json];//json就是得到的数据
  });
  }];
  [task resume];
  }
  //解析json，拿到步行时间

• (void)configWithData:(NSDictionary *)data{
  if (data) {
  NSArray *arrRouts=[data objectForKey:@"routes"];

    GMSPolyline *polyline = nil;
    if ([arrRouts count] > 0)
    {
        NSDictionary *routeDict = [arrRouts objectAtIndex:0];
        NSDictionary *routeOverviewPolyline = [routeDict objectForKey:@"overview_polyline"];
        NSString *points = [routeOverviewPolyline objectForKey:@"points"];
        GMSPath *path = [GMSPath pathFromEncodedPath:points];
        polyline = [GMSPolyline polylineWithPath:path];
        polyline.strokeWidth = 4.f;
        polyline.strokeColor =  MainColor1;
        polyline.map = self.googleMapView;
        
        GMSCoordinateBounds *bounds = [[GMSCoordinateBounds alloc] initWithPath:path];
        GMSCameraUpdate *update = [GMSCameraUpdate fitBounds:bounds];
        [self.googleMapView moveCamera:update];
        NSArray *routeArr = [data objectForKey:@"routes"];
        NSDictionary *routeDic = [NSDictionary dictionaryWithDictionary:[routeArr objectAtIndex:0]];
        NSString *time = [NSString stringWithFormat:@"%@",[[[[[routeDic objectForKey:@"legs"] objectAtIndex:0] objectForKey:@"duration"] objectForKey:@"text"] description]];//不行时间
  
        
    }else{
       
  
    }
  

  }else{
  }
  }
  按照以上步骤就能拿到步行时间，但是你有可能会遇到这个问题
  You have exceeded your daily request quota for this API. We recommend registering for a key at the Google Developers Console
  意思是说你每日请求这个api的数量已经超了，希望你可以去google后台申请一个key。此时我把谷歌服务的key拼接上如下：
  https://maps.googleapis.com/maps/api/directions/json?origin=39.99,116.31&destination=39.99,116.41&sensor=false&mode=walking&key=AIXXDDDDDDD
  然后再次请求会报如下错误：
  This IP, site or mobile application is not authorized to use this API key. How to fix this issue for an ios app?
  原因是我们谷歌服务的key和directions的key不一样的，所以不能乱用，纠结了好久最后在这里找到答案
  https://stackoverflow.com/questions/26195282/google-directions-api-failing-to-return-results-in-ios?noredirect=1&lq=1
  具体操作是：
  进入这个网址http://developers.google.com/maps/documentation/directions
  然后点击上边的获取密钥
  

  图片.png
  
  
  图片.png
  
  然后会有一个key，复制替换上边的key就行了。
  如果遇到请求失败，错误是-1002，是因为这个key中有特殊字符，例如--等，把url字符串uft8编码之后再请求，如下：
  NSString *urlStr = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/directions/json?origin=%f,%f&destination=%f,%f&sensor=false&mode=walking&language=en&key=AIzaXXXXXlwsvkCHQf--9xIKU0_zyMJ6To ",_coor.latitude,_coor.longitude,_lat,_lng];
  NSString *url = [urlStr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];