将“从当前位置的距离”添加到“NSMutableArray”

Question

我正在尝试将从当前位置的距离加载到我的数组中，但我似乎缺少一些东西。 我的表视图只显示"？"，这应该只在我的当前位置不工作时显示，但我的 NSLog 显示正确的位置。 请帮忙

更新：必须删除我的重新加载表视图，修复"？"，但现在我只得到 0.00 公里。 仍然缺少一些东西。 我的当前 Loc 在位置管理器中是正确的，但是当我尝试计算数组中的距离时，我丢失了它。

#import "AuthorViewController.h"
#import "Author.h"
#import <sqlite3.h>

@implementation AuthorViewController
@synthesize theauthors;
@synthesize currentLoc;
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
currentLoc = newLocation;
if (newLocation.horizontalAccuracy <= 100.0f) {
    [locMgr stopUpdatingLocation];
}
NSLog(@"Lat: %f, Long: %f", currentLoc.coordinate.latitude, currentLoc.coordinate.longitude);
[self.tableView reloadData];
}
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error
{
NSString *msg = [[NSString alloc]initWithString:@"Error obtaining location"];
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Error" message:msg delegate:nil cancelButtonTitle:@"Done" otherButtonTitles:nil];
[alert show];
}

#pragma mark - View lifecycle
- (void)viewDidLoad
{
[self barList];
[super viewDidLoad];
NSLog(@"Lat2: %f, Long2: %f", currentLoc.coordinate.latitude, currentLoc.coordinate.longitude);
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
locMgr = [[CLLocationManager alloc] init];
locMgr.delegate = self;
[locMgr startUpdatingLocation];
}

#pragma mark - Table view data source
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
return [self.theauthors count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
int rowCount = indexPath.row;
Author *author = [self.theauthors objectAtIndex:rowCount];

cell.textLabel.text = author.barName;
if (currentLoc == nil) {
    cell.detailTextLabel.text = [NSString stringWithFormat:@"?"];
}else
{
    cell.detailTextLabel.text = [NSString stringWithFormat:@"%.02f km", author.cachedDist];
}

return cell;
}

-(NSMutableArray *) barList{
theauthors = [[NSMutableArray alloc] init];
@try {
    NSFileManager *fileMgr = [NSFileManager defaultManager];
    NSString *dbPath = [[[NSBundle mainBundle] resourcePath ]stringByAppendingPathComponent:@"TulsaBars.sqlite"];
    BOOL success = [fileMgr fileExistsAtPath:dbPath];
    if(!success)
    {
        NSLog(@"Cannot locate database file '%@'.", dbPath);
    }
    if(!(sqlite3_open([dbPath UTF8String], &db) == SQLITE_OK))
    {
        NSLog(@"An error has occured: %@", sqlite3_errmsg(db));
    }

    const char *sql = "SELECT * FROM  TulsaBars";
    sqlite3_stmt *sqlStatement;
    if(sqlite3_prepare(db, sql, -1, &sqlStatement, NULL) != SQLITE_OK)
    {
        NSLog(@"Problem with prepare statement:  %@", sqlite3_errmsg(db));
    }else{
        while (sqlite3_step(sqlStatement)==SQLITE_ROW) {
            Author * author = [[Author alloc] init];
            author.barName = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement,1)];
            author.barAddress = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement,2)];
            author.barState = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement, 5)];
            author.barLat = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement, 8)];
            author.barLong = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement, 9)];
            author.cachedDist = [NSString stringWithUTF8String:(char *) sqlite3_column_text(sqlStatement, 10)];
            CLLocation *barLocation = [[CLLocation alloc] initWithLatitude:[author.barLat doubleValue] longitude:[author.barLong doubleValue]];
            CLLocationDistance distancekm = [currentLoc distanceFromLocation: barLocation]/1000;
            NSString *distanceString = [[NSString alloc] initWithFormat: @"%f", distancekm];
            author.cachedDist = distanceString;
            [theauthors addObject:author];
        }
    }
    sqlite3_finalize(sqlStatement);
}
@catch (NSException *exception) {
    NSLog(@"Problem with prepare statement:  %@", sqlite3_errmsg(db));
}
@finally {
    sqlite3_close(db);
    return theauthors;
}
}
@end

Answer 1

确保在

需要重绘表视图中的数据时调用[tableView reloadData]。

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