创建后更改注释图像 [英] change annotation image after its created

问题描述

我有一个自定义注释，它使用viewForAnnotation委托方法根据注释的类型设置其图像。我只使用1个注释代表汽车移动，并希望在检测到汽车移动和停止时更改图像。除了删除我的注释并重新添加它以引起眨眼之外，我怎么能这样做？

I have a custom annotation that sets its image based on the type of the annotation using the viewForAnnotation delegate method. Im only using 1 annotation that represents a car moving and want to change the image for when the car is detected to be moving and stopped. How could I go about this besides removing my annotation and re-adding it which causes a blink?

推荐答案

无论你在哪里检测到汽车状态已更改，使用 MKMapView 实例方法检索注释的当前视图 viewForAnnotation： 。这与 mapView：viewForAnnotation： 委托方法不同。

Wherever you detect that the car's state has changed, retrieve the annotation's current view using the MKMapView instance method viewForAnnotation:. This is not the same as the mapView:viewForAnnotation: delegate method.

之后获取注释的当前视图，您可以修改其属性，包括图像。

After getting the current view for the annotation, you can modify its properties including image.

同时确保 mapView：viewForAnnotation：委托方法具有相同的条件，可根据汽车注释的状态设置 image 。您可能希望将逻辑放在从两个位置调用的公共方法中（状态更改和委托方法），因此代码不会重复。

Also make sure the mapView:viewForAnnotation: delegate method has the same exact condition to set image based on the state of the car annotation. You may want to put the logic in a common method called from both places (where the state changes and the delegate method) so the code isn't duplicated.

例如，状态发生变化，你可能有：

For example, where the state changes, you might have:

//carAnnotation is your id<MKAnnotation> object
MKAnnotationView *av = [mapView viewForAnnotation:carAnnotation];
if (carAnnotation.isMoving)
    av.image = [UIImage imageNamed:@"moving.png"];
else
    av.image = [UIImage imageNamed:@"stopped.png"];

if 声明（或任何逻辑你必须设置 image ）是应该在 viewForAnnotation 委托方法中的部分。

The if statement (or whatever logic you have to set image) is the part that should also be in the viewForAnnotation delegate method.

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