显示自定义多个引脚会显示位置错误的引脚 [英] Displaying custom multiple pins shows wrong pins for locations
问题描述
这个问题已经困扰了我几个星期了！
This problem has been bugging me for a couple of weeks already!
我有一个标签栏应用程序.在一个选项卡上，我输入点，在另一个选项卡上，点显示在地图上.引脚应根据点的类型而有所不同.
I have a tab bar application. On one tab I am entering points, and on another tab, the points are displayed on a map. Pins should be different dependent on the types of points.
我面临的问题是，每当我从一个选项卡切换到另一个选项卡时，固定图像都会从应有的图像变为其他图像.例如，如果我在地图上有四个点，三个点显示为一个圆，一个显示为三角形，则该三角形将从一个点移动到另一个点.图像似乎随机变化.
The problem that I face is that every time I switch from one tab to another, the pin images change from what they should be to other images. For example, if I have four points on the map, three displayed as a circle and one as a triangle, the triangle will be moving around from one point to another. Images seem to change quite randomly.
所以，这是代码:
ViewController.m
ViewController.m
-(void) viewWillAppear:(BOOL)animated
{
// Select the type of map
if (isMapSelected == NO) {
self.mapView.mapType = MKMapTypeSatellite;
}
else {
self.mapView.mapType = MKMapTypeStandard;
}
// Add region to the map (center and span)
[self addRegion];
// Removing old annotation
[self.mapView removeAnnotations:mapLocations];
// Initializing arrays for the annotations
mapLocations = [[NSMutableArray alloc]init];
[self addAnnotation];
}
-(void) addAnnotation
{
CLLocationCoordinate2D mapLocation;
IGAMapAnnotation *mapAnnotation;
// Calculate how many points are included
NSInteger numberOfPoints = [coordinatesTempArray count];
// Annotations will be added only of the flight plan includes at least one point
if (numberOfPoints > 0)
{
// Trying to add coordinates from the array of coordinates
for (NSInteger i=0; i < ([coordinatesTempArray count]); i++) {
mapAnnotation = [[IGAMapAnnotation alloc]init];
// Taking a point in the array and getting its coordinates
self.mapCoordinates = [coordinatesTempArray objectAtIndex:i];
// Getting a point in the array and getting its lattitude and longitude
self.mapLatitude = [[self.mapCoordinates objectAtIndex:0]doubleValue];
self.mapLongitude = [[self.mapCoordinates objectAtIndex:1]doubleValue];
// Assigning the point coordinates to the coordinates to be displayed on the map
mapLocation.latitude = self.mapLatitude;
mapLocation.longitude = self.mapLongitude;
// Adding coordinates and title to the map annotation
mapAnnotation.coordinate = mapLocation;
mapAnnotation.title = [navaidNamesTempArray objectAtIndex:i];
mapAnnotation.subtitle = nil;
mapAnnotation.navaidType = [navaidTypesTempArray objectAtIndex:i];
// Adding the annotation to the array that will be added to the map
[mapLocations addObject:mapAnnotation];
}
// Adding annotations to the map
[self.mapView addAnnotations:mapLocations];
}
}
-(MKAnnotationView *) mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation
{
if([annotation isKindOfClass:[IGAMapAnnotation class]])
{
IGAMapAnnotation *myLocation = (IGAMapAnnotation *) annotation;
MKAnnotationView *annotationView = [mapView dequeueReusableAnnotationViewWithIdentifier:@"IGAMapAnnotation"];
if (annotationView == nil)
annotationView = myLocation.annotationView;
else
annotationView.annotation = annotation;
return annotationView;
}
else
return nil;
}
IGAMapAnnotation.m
IGAMapAnnotation.m
@synthesize coordinate = _coordinate;
@synthesize title = _title;
@synthesize subtitle = _subtitle;
@synthesize type = _type;
// Tried to have this init method but was never able to make it work. Without it, the program crashes too!!!!
-(id)initWithTitle:(NSString *)newTitle Type:(NSString *)type Location:(CLLocationCoordinate2D) newCoordinate
{
self = [super init];
if (self) {
_title = newTitle;
_coordinate = newCoordinate;
_type = type;
}
return self;
}
-(MKAnnotationView *) annotationView {
MKAnnotationView *annotationView = [[MKAnnotationView alloc]initWithAnnotation:self reuseIdentifier:@"IGAMapAnnotation"];
annotationView.enabled = YES;
annotationView.canShowCallout = YES;
annotationView.rightCalloutAccessoryView = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
if ([self.type isEqual: @"A"] || [self.type isEqual: @"B"] || [self.type isEqual: @"C"])
{
annotationView.image = [UIImage imageNamed:@"circle.png"];
}
else if ([self.type isEqual: @"D"])
{
annotationView.image = [UIImage imageNamed:@"triangle.png"];
}
else if ([self.type isEqual: @"E"])
{
annotationView.image = [UIImage imageNamed:@"square.png"];
}
else
{
annotationView.image = [UIImage imageNamed:@"oval.png"];
}
return annotationView;
}
@end
就是这样.到目前为止，这种行为对我来说毫无意义. 感谢您的帮助！
This is it. So far, the behaviour makes no sense to me. Thanks for your help!
推荐答案
这听起来像是注释视图的重用问题.
It sounds like an annotation view re-use issue.
重新显示注释时，它们将重新使用带有先前注释图像的视图.视图中的image属性未得到更新，因为它已被重新用于另一个注释.
When the annotations are re-displayed, they are re-using views with the images of previous annotations. The image property in the view is not being updated as it should be when it is re-used for another annotation.
在viewForAnnotation委托方法中，此代码看起来不正确:
In the viewForAnnotation delegate method, this code looks wrong:
MKAnnotationView *annotationView = [mapView dequeue...
if (annotationView == nil)
annotationView = myLocation.annotationView;
else
annotationView.annotation = annotation;
如果dequeue返回一个视图(即先前创建的视图，该视图可能是为不同类型的注释创建的)，则其annotation属性会更新，但其image属性未更新.
If the dequeue returns a view (ie. a previously-created view that may have been created for an annotation of a different type), its annotation property is updated but its image property is not updated.
现有代码仅在创建新的注释视图时(dequeue返回nil时)设置image属性.
The existing code only sets the image property when creating a new annotation view (when dequeue returns nil).
现在，注释 view 的创建和image设置代码位于注释 model 类IGAMapAnnotation中.最好创建一个自定义的MKAnnotationView类，该类在annotation属性更新时自动更新image属性.
Right now, the annotation view creation and image-setting code is in the annotation model class IGAMapAnnotation. It would be better to create a custom MKAnnotationView class that automatically updates the image property whenever its annotation property is updated.
但是，另一种选择是将所有逻辑放在viewForAnnotation委托方法本身中(并从IGAMapAnnotation类中删除annotationView方法).
However, another alternative is to put all the logic in the viewForAnnotation delegate method itself (and remove the annotationView method from the IGAMapAnnotation class).
更新的viewForAnnotation委托方法的示例:
Example of the updated viewForAnnotation delegate method:
-(MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation
{
if (! [annotation isKindOfClass:[IGAMapAnnotation class]])
{
//return default view if annotation is NOT of type IGAMapAnnotation...
return nil;
}
MKAnnotationView *annotationView = [mapView dequeueReusableAnnotationViewWithIdentifier:@"IGAMapAnnotation"];
if (annotationView == nil)
{
annotationView = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:@"IGAMapAnnotation"];
//these properties don't change per annotation
//so they can be set only when creating a new view...
annotationView.enabled = YES;
annotationView.canShowCallout = YES;
annotationView.rightCalloutAccessoryView = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
}
else
{
annotationView.annotation = annotation;
}
//whether we are using a completely new view or a re-used view,
//set the view's image based on the current annotation...
IGAMapAnnotation *myLocation = (IGAMapAnnotation *) annotation;
if ([myLocation.type isEqual: @"A"] || [myLocation.type isEqual: @"B"] || [myLocation.type isEqual: @"C"])
{
annotationView.image = [UIImage imageNamed:@"circle.png"];
}
else if ([myLocation.type isEqual: @"D"])
{
annotationView.image = [UIImage imageNamed:@"triangle.png"];
}
else if ([myLocation.type isEqual: @"E"])
{
annotationView.image = [UIImage imageNamed:@"square.png"];
}
else
{
annotationView.image = [UIImage imageNamed:@"oval.png"];
}
return annotationView;
}
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