使用枚举从数组中删除对象

Question

我有一系列词典。每个字典都包含纬度和经度，因此我从当前用户位置获取每个项目的距离。如果以英里为单位的距离大于20，则应从阵列中删除该特定字典。如果未从数组中删除字典，则会创建注释并将其添加到注释数组，然后在枚举完成后将其用于向地图添加注释。当我应该得到三个时，我只会添加一个注释，所以我知道我在枚举时做错了。

func checkDistanceAndAddPins() {
        for gym in gyms {
            var index = 0

            let gymLatitude = gym["latitude"]!!.doubleValue
            let gymLongitude = gym["longitude"]!!.doubleValue
            let gymLocation = CLLocation(latitude: gymLatitude, longitude: gymLongitude)
            let distance = gymLocation.distanceFromLocation(myLocation!)
            let distanceInMeters = NSNumber(double: distance)
            let metersDouble = distanceInMeters.doubleValue
            let miles = metersDouble * 0.00062137

            if miles > maxDistance {
                gyms.removeAtIndex(index)
            } else {
                let location = CLLocationCoordinate2D(latitude: gymLatitude, longitude: gymLongitude)
                gymAnnotation.title = gym["Name"] as? String
                gymAnnotation.subtitle = gym["Address"] as? String
                gymAnnotation.coordinate = location
                gymAnnotation.gymPhoneNumber = gym["Phone"] as? String
                if let website = gym["Website"] as? String {
                    gymAnnotation.gymWebsite = website
                }
                gymLocations.append(gymAnnotation)
            }

            index += 1
        }
        dispatch_async(dispatch_get_main_queue()) {
            self.gymMap.addAnnotations(self.gymLocations)
        }
    }