无法从mapview中删除所有注释

Question

I am getting problem while removing annotations from MKMapView. I have already search for same and found so many answers but couldn't find satisfactory ans. Below is my code summary:

I have created my custom class as MyMapViewPoints and created one function as

- initWithZTitle:(NSString *)title andCoordinate:(CLLocationCoordinate2D)location

Whenever I want to add annotation I simply create one object of MyMapViewPoints and

[mapView addAnnotation:newAnnotation];

When I want to remove all mapview points (annotations) I execute following code:

for (int i =0; i < [mapView.annotations count]; i++) 
{ 
    if ([[mapView.annotations objectAtIndex:i] isKindOfClass:[MyMapViewPoints class]]) 
    {    
        MyMapViewPoints *obj = (MyMapViewPoints *)[mapView.annotations objectAtIndex:i];
        if(obj.type != 1)
            [mapView removeAnnotation:[mapView.annotations objectAtIndex:i]];
    } 
}

But some of the annotation points remains on map. If I have added six points and tried to remove all using above code 2 mapview points (annotations) retains. Any ideas?

Answer 1

just try this code...

NSArray *existingpoints = mapView.annotations;
if ([existingpoints count] > 0)
    [mapView removeAnnotations:existingpoints];

UPDATE:

Also try this code...

for (int i =0; i < [mapView.annotations count]; i++) { 
    if ([[mapView.annotations objectAtIndex:i] isKindOfClass:[MyMapViewPoints class]]) {                      
         [mapView removeAnnotation:[mapView.annotations objectAtIndex:i]]; 
       } 
}

Answer 2

将您的数据源数组添加到以下行并删除所有annoation

[yourMapview removeAnnotations:datasourceArray];

Answer 3

You're modifying an array whilst also trying to loop through it. During the first iteration of that loop i=0 and if it matches the class you remove it from the annotations. If you remove the item at index 0, they all move up by one, so the one that was at index 1 is now at index 0. But you also increase i by one and during the next loop you look at index 1, completely missing the item that has now shifted to index 0.

index 0 1 2 3
item  A B C D

Check index 0, remove item at index 0.

index 0 1 2
item  B C D

Now check index at 1 and you've skipped B .

You should try these solutions How to delete all Annotations on a MKMapView

Also [yourMapView annotations] doesn't promise to return them in any specific order so every time you call it the indexes could be different. If you want to do any loop through the annotations you're best to save it as an NSArray* and refer to that copy from then on.