地图视图上的 iOS 刷新注释
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iOS refresh annotations on mapview
提问by Jon Erickson
I have a mapview where the annotation's coordinates are constantly being updated but when I use setCoordinate, the annotation does not move. How do I refresh the annotations to reflect their coordinates?
我有一个地图视图，其中注释的坐标不断更新，但是当我使用 setCoordinate 时，注释不会移动。如何刷新注释以反映其坐标？
- (void)updateUnits {
PFQuery *query = [PFQuery queryWithClassName:@"devices"];
[query whereKeyExists:@"location"];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error) {
for (PFObject *row in objects) {
PFGeoPoint *geoPoint = [row objectForKey:@"location"];
CLLocationCoordinate2D coord = { geoPoint.latitude, geoPoint.longitude };
for (id<MKAnnotation> ann in mapView.annotations) {
if ([ann.title isEqualToString:[row objectForKey:@"deviceid"]]) {
[ann setCoordinate:coord];
NSLog(@"latitude is: %f" , coord.latitude);
NSLog(@"Is called");
break;
}
else {
//[self.mapView removeAnnotation:ann];
}
}
}
}
else {
}
}];
}
回答by Rowan Freeman
Updated (to reflect the solution):
更新（以反映解决方案）：
Having your own custom annotations and implementing setCoordinate and/or synthesizing coordinate may cause issues.
拥有自己的自定义注释并实现 setCoordinate 和/或合成坐标可能会导致问题。
来源：http: //developer.apple.com/library/ios/#documentation/UserExperience/Conceptual/LocationAwarenessPG/AnnotatingMaps/AnnotatingMaps.html
Previous solution:
以前的解决方案：
You can simply remove all of the annotations and then re-add them.
您可以简单地删除所有注释，然后重新添加它们。
[mapView removeAnnotations:[mapView.annotations]];
[mapView addAnnotations:(NSArray *)];
or remove them and re-add them one by one:
或删除它们并一一重新添加：
for (id<MKAnnotation> annotation in mapView.annotations)
{
[mapView removeAnnotation:annotation];
// change coordinates etc
[mapView addAnnotation:annotation];
}
回答by Nathan
Dispatch the add annotation to the main thread rather then attempt to modify the UI on a background thread
将添加注释分发到主线程，而不是尝试在后台线程上修改 UI
dispatch_async(dispatch_get_main_queue()) {
self.mapView.addAnnotation(annotation)
}
回答by biomiker
Swift 3.0version of Nathan's answer (thank you Nathan):
Nathan 回答的Swift 3.0版本（谢谢 Nathan）：
DispatchQueue.main.async {
mapView.addAnnotation(annotation)
}
Side note, Nathan's answer should have far more upvotes. I actually needed this help with removing an annotation, the same issue exists and is fixed by dispatching the update to the main queue.
旁注，内森的回答应该有更多的赞成票。我实际上需要这个帮助来删除注释，同样的问题存在并且通过将更新分派到主队列来修复。
回答by oscar castellon
Try using [self.mapView removeAnnotations:self.mapView.annotations]:
尝试使用[self.mapView removeAnnotations:self.mapView.annotations]：
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
[self.mapView removeAnnotations:self.mapView.annotations];
PFQuery *query = [PFQuery queryWithClassName:@"caches"];
[query findObjectsInBackgroundWithBlock:^(NSArray *comments, NSError *error)
{
for (PFObject *comment in comments)
{
NSString *tit = comment[@"titulo"];
NSString *lat = comment[@"latitud"];
NSString *lon = comment[@"longitud"];
float latFloat = [lat floatValue];
float lonFloat = [lon floatValue];
CLLocationCoordinate2D Pin;
Pin.latitude = latFloat;
Pin.longitude = lonFloat;
MKPointAnnotation *annotationPoint = [[MKPointAnnotation alloc]init];
annotationPoint.coordinate = Pin;
annotationPoint.title = tit;
[self.mapView addAnnotation:annotationPoint];
}
}];
}
回答by Marek Manduch
For dark mode purposes I needed to refresh the views of annotations. I had to call also the delegate method to recreate the view of the annotations.
出于暗模式目的，我需要刷新注释视图。我还必须调用委托方法来重新创建注释视图。
- (void)traitCollectionDidChange:(UITraitCollection *)previousTraitCollection {
[super traitCollectionDidChange:previousTraitCollection];
if (@available(iOS 13.0, *)) {
if ([self.traitCollection hasDifferentColorAppearanceComparedToTraitCollection:previousTraitCollection]) {
for (id<MKAnnotation> annotation in self.mapView.annotations) {
[self.mapView removeAnnotation:annotation];
[self.mapView addAnnotation:annotation];
[self mapView:self.mapView viewForAnnotation:annotation];
}
}
}
}
回答by Claytog
Removing all existing annotations, and re-adding the new or updated annotation list will refresh the mapView. Firstly I tried:
删除所有现有注释，并重新添加新的或更新的注释列表将刷新 mapView。首先我试过：
mapView.annotations.removeAll()
but received the error:
但收到错误：
"Value of type '(MKMapRect) -> Set<AnyHashable>' has no member 'removeAll'"
However this worked:
但是这有效：
for annotation in mapView.annotations{
mapView.removeAnnotation(annotation)
}
// .. code to add the new or updated annotation list
回答by apollovishwas
Just Add
只需添加
mapView.reloadStyle(self)
