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

origin=起點(diǎn)經(jīng)緯度 destination=終點(diǎn)經(jīng)緯度
然后用請(qǐng)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就是得到的數(shù)據(jù)
  });
  }];
  [task resume];
  }
  //解析json，拿到步行時(shí)間

• (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]];//不行時(shí)間
  
        
    }else{
       
  
    }
  

  }else{
  }
  }
  按照以上步驟就能拿到步行時(shí)間，但是你有可能會(huì)遇到這個(gè)問(wèn)題
  You have exceeded your daily request quota for this API. We recommend registering for a key at the Google Developers Console
  意思是說(shuō)你每日請(qǐng)求這個(gè)api的數(shù)量已經(jīng)超了，希望你可以去google后臺(tái)申請(qǐng)一個(gè)key。此時(shí)我把谷歌服務(wù)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
  然后再次請(qǐng)求會(huì)報(bào)如下錯(cuò)誤：
  This IP, site or mobile application is not authorized to use this API key. How to fix this issue for an ios app?
  原因是我們谷歌服務(wù)的key和directions的key不一樣的，所以不能亂用，糾結(jié)了好久最后在這里找到答案
  https://stackoverflow.com/questions/26195282/google-directions-api-failing-to-return-results-in-ios?noredirect=1&lq=1
  具體操作是：
  進(jìn)入這個(gè)網(wǎng)址http://developers.google.com/maps/documentation/directions
  然后點(diǎn)擊上邊的獲取密鑰
  

  圖片.png
  
  
  圖片.png
  
  然后會(huì)有一個(gè)key，復(fù)制替換上邊的key就行了。
  如果遇到請(qǐng)求失敗，錯(cuò)誤是-1002，是因?yàn)檫@個(gè)key中有特殊字符，例如--等，把url字符串uft8編碼之后再請(qǐng)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];