ios - MapKit - 更新 MapView 以通过计时器显示移动注释
<p><p>我想要达到的最终状态是让一个正在运行的计时器刷新“车辆”<code>annotations</code> 的集合。 <code>annotation</code> <code>coordinates</code> 使用 Timer 每 60 秒成功刷新一次，但用户必须调用 mapView:<code>regionWillChangeAnimated</code> 和 mapView:<code>regionWillChangeAnimated</code> 代表。这些代表正在正确工作并移动 Vehicle <code>annotations</code>，但我希望 <code>annotations</code> 能够自主移动，而无需用户与屏幕进行交互。 </p>
<p>这是我的方法:</p>
<p>1) 启动计时器.. 完美!</p>
<pre><code>//|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
#pragma mark Timers
//|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
dispatch_source_t CreateDispatchTimer(uint64_t interval,
uint64_t leeway, dispatch_queue_t queue, dispatch_block_t block)
{
dispatch_source_t timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
if (timer)
{
dispatch_source_set_timer(timer, dispatch_time(DISPATCH_TIME_NOW, interval), interval * NSEC_PER_SEC, (1ull * NSEC_PER_SEC) / 10);
dispatch_source_set_event_handler(timer, block);
dispatch_resume(timer);
}
return timer;
}
- (void)startTimer
{
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
double secondsToFire = 60.000f;
double secondsLeeway = 2.000f;
_timer = CreateDispatchTimer(secondsToFire, secondsLeeway, queue, ^{
// Do something
//Method Call to Refresh NSMutableArray of Vehicle Models
;
NSLog(@"TIMER TASK CALLED");
});
}
- (void)cancelTimer
{
if (_timer) {
dispatch_source_cancel(_timer);
_timer = nil;
}
}
</code></pre>
<p>计时器用于通过调用 <code>(void)RefreshVehicles</code> 获取最新的 Vehicles 并将其加载到 <code>NSMutable Array</code> 中，这将更新最新的<code>坐标</code> 用于更新 Vehicle <code>annotation</code> 的每个对象。我正在使用 <code>NSNotification</code> 来了解异步网络调用和 <code>SQLite</code> 何时更新车辆记录完成。当通知触发时，我将删除任何现有的 Vehicle <code>annotations</code>，然后通过调用 <code>addVehiclesToMap</code> 来更新本地 Vehicle <code>NSMutable Array</code> 以添加新的<code>注释</code>到 map :</p>
<pre><code>//|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
#pragma mark Notification Listener
//|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
- (void)RefreshVehicles:(NSNotification *)notif {
NSLog(@"++++++++++++++++++++++++++++++++++++++++Vehicles UPDATED!");
** POST SOLUTION REMARK:MOVED REMOVE ANNOTATION LOGIC TO: (void)addVehiclesToMap
//** MOVED //If it already Exists, Remove it, Must redraw vehicles because they are moving.
//** MOVED for (id <MKAnnotation> annotation in self.mapView.annotations)
//** MOVED{
//** MOVED//Only Remove Vehicles, Leave Stations, they are static
//** MOVED if (])
//** MOVED{
//** MOVED ;
//** MOVED}
//** MOVED}
//Load Vehicle Collection
self.vehicleCollection = [ vehicleReturnAll];
;
}
</code></pre>
<p><code>addVehiclesToMap</code> 的方法如下:
**POST SOLUTION REMARK:在 <code>Main Thread</code> 上实现 Anna 的解决方案以更新 map<code>annotations</code> 后，我开始收到以下错误:<code>*** Terminating app由于未捕获的异常 'NSGenericException'，原因:'*** Collection <__NSArrayM: 0x16d94af0> 在枚举时发生了变异。</code>'</p>
<p>这是因为我从后台线程的计时器刷新中删除了注释。为了解决这个问题，我也在主线程中实现了 <code>;</code>。**</p>
<pre><code>/*
----- VEHICLES -----
*/
- (void)addVehiclesToMap {
//If it already Exists, Remove it, Must redraw vehicles because they are moving.
for (id <MKAnnotation> annotation in self.mapView.annotations)
{
//Only Remove Vehicles, Leave Stations, they are static
if (])
{
//Remove Vehicle Annotation to MapView on the Main Thread
dispatch_async(dispatch_get_main_queue(), ^{
;
});
}
}
//Loop through Vehicle Collection and generate annotation for each Vehicle Object
for (VehicleModel *vehicle in vehicleCollection) {
//New Vehicle Annotation Instance
VehicleAnnotation *myVehicleAnnotation = [ init];
myVehicleAnnotation.coordinate = CLLocationCoordinate2DMake(, );
myVehicleAnnotation.vehicleId = ;
myVehicleAnnotation.title = vehicle.vehicleLabel;
myVehicleAnnotation.subtitle = vehicle.vehicleIsTrainDelayed;
**POST SOLUTION REMARK: PER ANNA'S SOLUTION, MOVE addAnnodation TO MAIN THREAD:**
//MODIFIED THIS:** ;
**//TO THIS:**
//Add Vehicle Annotation to MapView on the Main Thread
dispatch_async(dispatch_get_main_queue(), ^{
;
});**
}
</code></pre>
<p>}</p>
<p>接下来是 <code>viewAnnotation</code> 委托(delegate)的代码:</p>
<pre><code>//|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
#pragma mark MKAnnotationView Delegate
//|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
- (MKAnnotationView *)mapView:(MKMapView *)theMapView viewForAnnotation:(id <MKAnnotation>)annotation
{
// if it's the user location, just return nil.
if (])
return nil;
// handle our two custom annotations
//
if (]) /// for Vehicles Only
{
//Important, can't use annotation, this lets the compiler know that the annotation is actually an StationAnnotation object.
VehicleAnnotation *vehicleAnnotation = (VehicleAnnotation *)annotation;
//Reuse existing Annotation
NSString* AnnotationIdentifier = vehicleAnnotation.vehicleId.lowercaseString;
MKPinAnnotationView* pinView = (MKPinAnnotationView *);
if (!pinView)
{
//Set unique annotation identifierexp: 304 (The Vehicles's Unique Number)
NSString* AnnotationIdentifier = vehicleAnnotation.vehicleId.lowercaseString;
MKAnnotationView *annotationView = [ initWithAnnotation:annotation reuseIdentifier:AnnotationIdentifier];
annotationView.canShowCallout = YES;
NSString *vehicleFlagIcon = [@"map_train_green_" stringByAppendingString:vehicleAnnotation.vehicleId.lowercaseString];
UIImage *flagImage = ;
CGRect resizeRect;
resizeRect.size = flagImage.size;
CGSize maxSize = CGRectInset(self.view.bounds,
,
).size;
maxSize.height -= self.navigationController.navigationBar.frame.size.height + ;
if (resizeRect.size.width > maxSize.width)
resizeRect.size = CGSizeMake(maxSize.width, resizeRect.size.height / resizeRect.size.width * maxSize.width);
if (resizeRect.size.height > maxSize.height)
resizeRect.size = CGSizeMake(resizeRect.size.width / resizeRect.size.height * maxSize.height, maxSize.height);
resizeRect.origin = (CGPoint){0.0f, 0.0f};
UIGraphicsBeginImageContext(resizeRect.size);
;
UIImage *resizedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
annotationView.image = resizedImage;
annotationView.opaque = NO;
NSString *vehicleLogo = [@"map_train_green_" stringByAppendingString:vehicleAnnotation.vehicleId.lowercaseString];
UIImageView *sfIconView = [ initWithImage:];
annotationView.leftCalloutAccessoryView = sfIconView;
return annotationView;
}
else
{
pinView.annotation = annotation;
}
return pinView;
}
return nil;
}
</code></pre>
<p>接下来我确实有逻辑要删除，然后使用以下委托(delegate)重新添加 <code>annotations</code>。这些委托(delegate)工作得很好，但需要用户与屏幕交互。我正在尝试每隔 X 秒刷新一次 map 。到目前为止，要查看对 <code>annotation</code> 位置的任何更改，我必须触摸屏幕并移动 map 以调用这些删除操作。我仍然无法看到车辆自动移动而无需执行交互。</p>
<p><strong>发布解决方案备注:我删除了这些代表，因为他们正在对车辆注释执行不必要的更新，从而在 map 被触摸和移动时使图标闪烁......让计时器完成工作</strong> </p>
<pre><code>**// DELETED** -(void)mapView:(MKMapView *)theMapView regionWillChangeAnimated:(BOOL)animated { ...Annotation tear down and rebuild code here }
**//DELETED** -(void)mapView:(MKMapView *)theMapView didUpdateUserLocation:(MKUserLocation *)userLocation { ...Annotation tear down and rebuild code here }
</code></pre>
<p><strong>我是否已经接近解决方案？提前谢谢...</strong> </p></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p>尝试在主线程上调用 <code>addAnnotation</code>，以便 UI 更新不会出现延迟:</p>
<pre><code>dispatch_async(dispatch_get_main_queue(), ^{
;
});
</code></pre>
<p><br/>
<br/>
<em>一个不相关的建议:</em><br/>
无需删除和重新添加车辆注释，您只需更新现有车辆的 <code>coordinate</code> 属性， mapView 将自动移动注释 View 。这可能会导致稍微平滑的效果，尽管实现逻辑稍微困难一些(例如，您需要在 mapView<code>annotations</code> 数组中找到现有的车辆注释并更新它而不是创建新的<code>VehicleAnnotation</code>)。您还必须考虑新车辆并删除不再存在的车辆的注释。</p>
<p><br/>
<em>另一个不相关的建议:</em><br/>
而不是这种迂回和神秘的方式来设置坐标:</p>
<pre><code>NSString *coord = [NSString stringWithFormat:@"{%@,%@}",
,
];
CGPoint point = CGPointFromString(coord);
myVehicleAnnotation.coordinate = CLLocationCoordinate2DMake(point.x, point.y);
</code></pre>
<p>我建议采用这种更直接、更简洁的方法:</p>
<pre><code>myVehicleAnnotation.coordinate = CLLocationCoordinate2DMake(
, );
</code></pre></p>
<p style="font-size: 20px;">关于ios - MapKit - 更新 MapView 以通过计时器显示移动注释，我们在Stack Overflow上找到一个类似的问题：
<a href="https://stackoverflow.com/questions/21446917/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/21446917/
</a>
</p>
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