如何从UITableView中删除行？

This has been bugging me for hours now and i have not been able to figure it out.

这已经困扰了我几个小时了，我无法弄明白。

I am importing data into a tableview using core data and NSMutableArray. As shown below.

我使用核心数据和NSMutableArray将数据导入到tableview中。如下所示。

CORE DATA ARRAY

核心数据阵列

NSMutableArray *mutableFetchResults  = [CoreDataHelper getObjectsFromContext:@"Spot" :@"Name" :YES :managedObjectContext];
self.entityArray = mutableFetchResults;

TABLE VIEW

表视图

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    NSManagedObject *object = (NSManagedObject *)[entityArray objectAtIndex:indexPath.row];

    NSString *CellIdentifier = @"Cell";

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



    NSString *lat1 = [object valueForKey:@"Email"];

    //NSLog(@"Current Spot Latitude:%@",lat1);

    float lat2 = [lat1 floatValue];
    //NSLog(@"Current Spot Latitude Float:%g", lat2);

    NSString *long1 = [object valueForKey:@"Description"];

    //NSLog(@"Current Spot Longitude:%@",long1);

    float long2 = [long1 floatValue];
    //NSLog(@"Current Spot Longitude Float:%g", long2);

    //Getting current location from NSDictionary

    CoreDataTestAppDelegate *appDelegate = (CoreDataTestAppDelegate *) [[UIApplication sharedApplication] delegate];
    NSString *locLat = [NSString stringWithFormat:appDelegate.latitude];
    float locLat2 = [locLat floatValue];
    //NSLog(@"Lat: %g",locLat2);

    NSString *locLong = [NSString stringWithFormat:appDelegate.longitude];
    float locLong2 = [locLong floatValue];
    //NSLog(@"Long: %g",locLong2);

    //Distance Shizzle
    //Prime's Location
    CLLocation *loc1 = [[CLLocation alloc] initWithLatitude:lat2 longitude:long2];
    //Home Location
    CLLocation *loc2 = [[CLLocation alloc] initWithLatitude:locLat2 longitude:locLong2];

    double distance = [loc1 getDistanceFrom: loc2] / 1000;

    int myInt = (int)(distance + (distance>0 ? 0.5 : -0.5));

    //NSLog(@"INT VAL :%i", myInt);

    NSMutableString* converted = [NSMutableString stringWithFormat:@"%.1f", distance];

    [converted appendString: @" Km"];

    //NSLog(@"Distance between Prime and home = %g", converted);

    if (myInt < 11) {
        cell.textLabel.text = [object valueForKey:@"Name"];
        cell.detailTextLabel.text = [NSString stringWithFormat:converted];
    }
    else {


    }

    // Configure the cell...

    return cell;
}

I am trying to get the table only to display results that are within a certain distance. This method here works apart from the fact that the results over a certain distance are still in the table, they are just not graphically visible.

我试图让表格只显示一定距离内的结果。这种方法除了在一定距离内的结果仍在表格中之外，它们只是图形上不可见。

I am led to believe that i have to carry out the filtering process before the formatting the table but i can not seem to do this.

我被引导相信我必须在格式化表之前执行过滤过程，但我似乎无法做到这一点。

Please help. My xcode skills are not brilliant so code suggestions would be helpfull.

请帮忙。我的xcode技能并不出色，所以代码建议会有所帮助。

1 个解决方案

#1

You don't want to be trying to filter the results in cellForRowAtIndexPath:, because there isn't a direct correspondence between the index passed to cellForRowAtIndexPath: and the entries in you entityArray. For example, if your entire entityArray has 10 elements, but only 3 are within the desired distance, indexes into entityArray will go from 0..9, but only cells 0..2 in your tableview will exist.

您不希望尝试过滤cellForRowAtIndexPath：中的结果，因为传递给cellForRowAtIndexPath的索引与您entityArray中的条目之间没有直接对应关系。例如，如果整个entityArray有10个元素，但只有3个元素在所需距离内，则entityArray的索引将从0..9开始，但只有tableview中的单元格0..2存在。

You should create a separate, filtered, NSMutableArray at the time you fetch your results, and display the contents of that array in your TableView.

您应该在获取结果时创建单独的，已过滤的NSMutableArray，并在TableView中显示该数组的内容。

The other reason you need to do your filtering in advance is that you need to implement the -numberOfRowsInSection: method in your tableview controller, to tell the tableview how many rows there are. You obviously can't do what without doing the filtering.

您需要提前进行过滤的另一个原因是您需要在tableview控制器中实现-numberOfRowsInSection：方法，以告诉tableview有多少行。如果不进行过滤，你显然无法做到。

Edit:

编辑：

You could create the filtered array doing something like:

您可以创建过滤后的数组，例如：

@property (nonatomic, retain) NSMutableArray *filteredArray;

self.filteredArray = [NSMutableArray array]; // start w/ empty array

for (MyObject *obj in self.entityArray) { // use fast enumeration to look at each element
    if ([obj shouldBeAdded]) { // or whatever function you use to test distance
         [self.filteredArray addObject:obj]; // add objects that match
    }
}

(and don't forget to release filteredArray in your -dealloc method)

（并且不要忘记在-dealloc方法中释放filteredArray）

#1