动画删除注释

Question

我有一张地图和一组注释，每个注释都有一个“父”属性。目前，当我添加注释时，我实现 didAddAnnotationViews 方法来对这些注释进行动画处理，以便它们看起来来自其父级的坐标。在删除注释期间有没有办法做到这一点？当我从地图中删除注释时，我希望它以动画方式显示到其父坐标，据我所知，在删除注释时没有 didAddAnnotationViews 的等效项。

Answer 1

在从地图中删除注记之前对其进行动画处理，并在动画完成后执行删除操作。代码可能如下所示：

- (void) removeMyAnnotation:(MyAnnotation*)annotation{
   [UIView animateWithDuration:1.0f
                    animations:^(void){
                         annotation.coordinate = annotation.parentAnnotation.coordinate;
                    }
                    completion:^(BOOL finished)completion{
                        [mapView removeAnnotation:annotation];
                    }
}

Answer 2

您不应该像 @Vladimir 的回答那样推迟调用 removeAnnotation ，因为 MKMapView 的状态可能会在动画过程中发生变化。

当从动画完成块调用 removeAnnotation 时，可以从 MapView 添加/删除另一个注释 - 因此，在某些情况下，您最终可能会删除错误的注释集。

我为 MKMapView 编写了这个类别，您可以使用它以安全的方式删除动画注释：

@interface MKMapView (RemoveAnnotationWithAnimation)

- (void)removeAnnotation:(id <MKAnnotation>)annotation animated:(BOOL)animated;
- (void)removeAnnotations:(NSArray *)annotations animated:(BOOL)animated;

@end

以及 .m 文件：

@implementation MKMapView (RemoveAnnotationWithAnimation)

- (void)removeAnnotation:(id <MKAnnotation>)annotation animated:(BOOL)animated
{
    [self removeAnnotations:@[annotation] animated:animated];
}

- (void)removeAnnotations:(NSArray *)annotations animated:(BOOL)animated
{
    if (animated) {
        NSSet * visibleAnnotations = [self annotationsInMapRect:self.visibleMapRect];
        NSMutableArray * annotationsToRemoveWithAnimation = [NSMutableArray array];
        for (id<MKAnnotation> annotation in annotations) {
            if ([visibleAnnotations containsObject:annotation]) {
                [annotationsToRemoveWithAnimation addObject:annotation];
            }
        }
        NSMutableArray * snapshotViews = [NSMutableArray array];
        for (id<MKAnnotation> annotation in annotationsToRemoveWithAnimation) {
            UIView * annotationView = [self viewForAnnotation:annotation];
            if (annotationView) {
                UIView * snapshotView = [annotationView snapshotViewAfterScreenUpdates:NO];
                snapshotView.frame = annotationView.frame;
                [snapshotViews addObject:snapshotView];
                [[annotationView superview] insertSubview:snapshotView aboveSubview:annotationView];
            }
        }
        [UIView animateWithDuration:0.5
                         animations:^{
                             for (UIView * snapshotView in snapshotViews) {
                                 // Change the way views are animated if you want
                                 CGRect frame = snapshotView.frame;
                                 frame.origin.y = -frame.size.height;
                                 snapshotView.frame = frame;
                             }
                         }
                         completion:^(BOOL finished) {
                             for (UIView * snapshotView in snapshotViews) {
                                 [snapshotView removeFromSuperview];
                             }
                         }];
    }
    [self removeAnnotations:annotations];
}

@end