【发布时间】:2014-08-31 10:23:31
【问题描述】:
我在地图视图中添加自定义注释。根据应用程序的内部模型,注释可以改变颜色和标题(尽管位置可能不会改变)。我在方法中使用dequeueReusableAnnotationViewWithIdentifier
- (MKAnnotationView *)mapView:(MKMapView *) viewForAnnotation:(id <MKAnnotation>)
奇怪的是,当模型更改时,注释被“刷新”以使用正确的标题和颜色(我只是使用removeAnnotations: 并添加新的),但后来在使用地图时,一些旧的注释与错误的颜色出队。每次模型更改时,我都会使用不同的标识符。
代码如下:
- (MKAnnotationView *)mapView:(MKMapView *)theMapView viewForAnnotation:(id <MKAnnotation>)annotation{
// in case it's the user location, we already have an annotation, so just return nil
if ([annotation isKindOfClass:[MKUserLocation class]]){
return nil;
}
if ([annotation isKindOfClass:[APGSAnnotation class]]){
APGSAnnotation *gsn = (APGSAnnotation*) annotation;
NSString *GSAnnotationIdentifier = [NSString stringWithFormat:@"gid_%lu_%@", (unsigned long)gsn.gs.gID, self.car.energyType];
MKAnnotationView *markerView = [theMapView dequeueReusableAnnotationViewWithIdentifier:GSAnnotationIdentifier];
if (markerView == nil) {
MKAnnotationView *annotationView = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:GSAnnotationIdentifier];
annotationView.canShowCallout = YES;
annotationView.image = [self customizeAnnotationImage:gsn.gs];
annotationView.opaque = NO;
UIImageView *sfIconView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:gsn.logo]];
annotationView.leftCalloutAccessoryView = sfIconView;
// http://stackoverflow.com/questions/8165262/mkannotation-image-offset-with-custom-pin-image
annotationView.centerOffset = CGPointMake(0,-annotationView.image.size.height/2);
UIButton *rightButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
[rightButton addTarget:nil action:nil forControlEvents:UIControlEventTouchUpInside];
annotationView.rightCalloutAccessoryView = rightButton;
return annotationView;
}else{
markerView.annotation = annotation;
return markerView;
}
}
return nil;
}
以及自定义方法
- (UIImage*)customizeAnnotationImage:(APGS*)gs{
UIImage *markerImage;
if (gs.gID == self.best.gID) {
markerImage = [UIImage imageNamed:@"marker_red.png"];
}else if (gs.type == k1){
markerImage = [UIImage imageNamed:@"marker_blue.png"];
}else if (gs.type == k2){
markerImage = [UIImage imageNamed:@"marker_green.png"];
}else if (gs.type == k3){
markerImage = [UIImage imageNamed:@"marker_purple.png"];
}else if (gs.type == k4){
markerImage = [UIImage imageNamed:@"marker_brown.png"];
}
UIImage *logoImage = [UIImage imageNamed:gs.logo];
// size the flag down to the appropriate size
CGRect resizeRect;
resizeRect.size = markerImage.size;
CGSize maxSize = CGRectInset(self.view.bounds, kAnnotationPadding, kAnnotationPadding).size;
maxSize.height -= self.navigationController.navigationBar.frame.size.height + kCallOutHeight;
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 = CGPointMake(0.0, 0.0);
float initialWidth = resizeRect.size.width;
UIGraphicsBeginImageContextWithOptions(resizeRect.size, NO, 0.0f);
[markerImage drawInRect:resizeRect];
resizeRect.size.width = resizeRect.size.width/2;
resizeRect.size.height = resizeRect.size.height/2;
resizeRect.origin.x = resizeRect.origin.x + (initialWidth - resizeRect.size.width)/2;
resizeRect.origin.y = resizeRect.origin.y + kLogoHeightPadding;
[logoImage drawInRect:resizeRect];
// Create string drawing context
UIFont *font = [UIFont fontWithName:@"DBLCDTempBlack" size:11.2];
NSString * num = [NSString stringWithFormat:@"%4.3f",[gs getL]];
NSDictionary *textAttributes = @{NSFontAttributeName: font,
NSForegroundColorAttributeName: [UIColor whiteColor]};
CGSize textSize = [num sizeWithAttributes:textAttributes];
NSStringDrawingContext *drawingContext = [[NSStringDrawingContext alloc] init];
//adjust center
if (resizeRect.size.width - textSize.width > 0) {
resizeRect.origin.x += (resizeRect.size.width - textSize.width)/2;
}else{
resizeRect.origin.x -= (resizeRect.size.width - textSize.width)/2;
}
resizeRect.origin.y -= kTextPadding;
[num drawWithRect:resizeRect
options:NSStringDrawingUsesLineFragmentOrigin
attributes:textAttributes
context:drawingContext];
UIImage *resizedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return resizedImage;
}
注释应根据汽车类型改变颜色。
【问题讨论】:
-
从视图中取出后,您应该在返回视图之前重置所有相关属性
-
我已针对“原样”代码编辑了我的问题。
-
另外,您的代码不会在所有路径中返回值 - 这会导致问题
-
请注意,注释视图的属性应根据
annotation参数更新,无论视图是创建还是出列。因此,如果...正在这样做,它应该在整个 if/else 语句之后,return应该在之后移动。 -
问题似乎是当视图出队时(当 markerView != nil 时),代码不会更新视图的图像和其他属性(它只是更新注释属性)。因此,可能发生的情况是注释重新使用先前注释中的视图,该注释具有不同的图像等。
标签: ios objective-c mapkit