Question

我有一个应用程序，其中列出了许多将纬度和经度存储在数据库中的场所。我用json填充列表。然后我在动态表格中显示结果。在牢房中，我的距离以公里为单位。我通过获取用户当前位置并使用场地坐标计算距离来找到此距离。

它工作正常但我的问题是视图加载，距离错误，直到用户位置更新3-5秒后，它显示正确的距离。

我获取用户位置并在viewdidload中填充单元格。

我的问题是：是否可以在上一个视图中获取用户的位置并将其传递到此视图，以便最初显示的距离正确？

以下是代码：

我首先在viewdidload中获取用户loc：

- (void)viewDidLoad {
    [super viewDidLoad];
    locationManager = [[CLLocationManager alloc] init];
    locationManager.delegate = self;
    locationManager.distanceFilter = kCLDistanceFilterNone; // whenever we move
    locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters; // 100 m
    [locationManager startUpdatingLocation];

然后我得到我的json数据等等。然后我做tableView：

// Customize the number of rows in the table view.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return [rows count];
}

- (void)locationManager:(CLLocationManager *)manager
    didUpdateToLocation:(CLLocation *)newLocation
           fromLocation:(CLLocation *)oldLocation
{
    //    int degrees = newLocation.coordinate.latitude;
    //    double decimal = fabs(newLocation.coordinate.latitude - degrees);
    //    int minutes = decimal * 60;
    //    double seconds = decimal * 3600 - minutes * 60;
    //    NSString *lat = [NSString stringWithFormat:@"%d° %d' %1.4f\"", 
    //                     degrees, minutes, seconds];
    NSString *lat = [NSString stringWithFormat:@"%f", newLocation.coordinate.latitude];
    latLabel.text = lat;
    //    degrees = newLocation.coordinate.longitude;
    //    decimal = fabs(newLocation.coordinate.longitude - degrees);
    //    minutes = decimal * 60;
    //    seconds = decimal * 3600 - minutes * 60;
    //    NSString *longt = [NSString stringWithFormat:@"%d° %d' %1.4f\"", 
    //                       degrees, minutes, seconds];
    NSString *longt = [NSString stringWithFormat:@"%f", newLocation.coordinate.longitude];
    longLabel.text = longt;

    //CGFloat Alat = [lat floatValue];
    //CGFloat Alon = [longt floatValue];
    self.aalat = lat;
    self.aalon = longt;

}



// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
    }

    // Configure the cell.
    NSDictionary *dict = [rows objectAtIndex: indexPath.row];
    THELATITUDE = [dict objectForKey:@"L_LAT"];
    THELONGITUDE = [dict objectForKey:@"L_LON"];
    CGFloat Nlat = [THELATITUDE floatValue];
    CGFloat Nlon = [THELONGITUDE floatValue];
    CGFloat NNlat = [aalat floatValue];
    CGFloat NNlon = [aalon floatValue];
//    NSLog(@"lat1: %f", Nlat);
//    NSLog(@"Lon1: %f", Nlon);
//    NSLog(@"lat2: %f", NNlat);
//    NSLog(@"Lon2: %f", NNlon);
//    NSLog(@"aalat: %@", aalat);
//    NSLog(@"aalon: %@", aalon);


    CLLocation *location1 = [[CLLocation alloc] initWithLatitude:Nlat longitude:Nlon];
    CLLocation *location2 = [[CLLocation alloc] initWithLatitude:NNlat longitude:NNlon];
   // NSLog(@"Distance i meters: %f", [location1 getDistanceFrom:location2]);
    float mesafe1 = [location1 getDistanceFrom:location2 ] /1000;
    int x1 = mesafe1 * 100.0;
    float mesafe2 = (float) x1 / 100.0;


    //Create a string.
    NSString *strOne = [[NSString alloc] init];
    NSString *strTwo = [[NSString alloc] init];
    NSString *strThree = [[NSString alloc] init];
    NSString *strFour = [[NSString alloc] init];
    NSString *strFive = [[NSString alloc] init];


    //Append strings.
    strOne =  @"MESAFE: ";
    strTwo = [NSString stringWithFormat:@"%0g", mesafe2];
    strThree = @" kilometre";
    strFour = [strOne stringByAppendingString:strTwo];
    strFive = [strFour stringByAppendingString:strThree];

    NSString *mesafe = strFive;


    cell.textLabel.text = [dict objectForKey:@"L_NAME"];
    //cell.detailTextLabel.text = [dict objectForKey:@"LISTING_ID"];
    cell.detailTextLabel.text = mesafe;



    [cell.textLabel setTextColor:[UIColor blackColor]];

    return cell;
}

Answer 1

使用NSUserDefault方法保存用户当前位置的纬度和经度，并将其用于您的视图。使位置更新管理器开始不停止，这样你就可以获得精确的纬度和经度

在用户位置更新时使用它

     [[NSUserDefaults standardUserDefaults] setObject:latitude forKey:@"latitude"];
 [[NSUserDefaults standardUserDefaults] setObject:latitude forKey:@"longitude"];

在计算距离的地方使用它

   NSString *lat = [[NSUserDefaults standardUserDefaults] objectForKey:@"latitude"];
 NSString *long =  [[NSUserDefaults standardUserDefaults] objectForKey:@"longitude"];

Answer 2

在上一个视图中获取用户的位置，然后在加载listview时将数据发送到这样的视图（在这种情况下userLocation可以是具有长和纬度的JSON字符串）

- (void) loadVenuesListView {
    VenuesViewController *venuesView = [[VenuesViewController alloc] initWithNibName:@"VenuesViewController" bundle:nil];
    venuesView.userLocation = fetchedUserLocation;
    [[self navigationController] pushViewController:venuesView animated:YES];
    [venuesView release];   
}

然后在VenuesViewController中你必须创建一个属性：

@property (nonatomic, retain) NSString *userLocation;

iPhone应用程序显示表中的场地距离

2 个答案: