[英]iOS - MKMapView Overlay won't render when I move methods to another class
Working on cleaning up my code so I can render different overlays of trails atop an MKMapView apple map, depending... 正在努力清理我的代码,以便我可以在MKMapView苹果地图上面渲染不同的路径叠加,具体取决于......
Currently I have an apple map coming up and I can get a specific overlay trail image rendered (over an MKMapView object) when I use two methods -addOverlayTo: and mapView:rendererForOverlay - within my view controller class "ParkMapVC". 目前我有一张苹果地图,当我在视图控制器类“ParkMapVC”中使用两个方法-addOverlayTo:和mapView:rendererForOverlay时,我可以获得一个特定的叠加轨迹图像(通过MKMapView对象)。 When I move those two methods to another more generic class "ParkMapOverlay" - an NSObject inheriting class, I can get the "addOverlayTo:" method I message directly to execute, but not the mapView:rendererForOverlay method.
当我将这两个方法移动到另一个更通用的类“ParkMapOverlay” - 一个NSObject继承类时,我可以直接执行“addOverlayTo:”方法,而不是mapView:rendererForOverlay方法。
I didn't directly message mapView:rendererForOverlay in the original (working) version, but from following the debugger, it seemed it was triggered by my addOverlayTo: method - I think by the object returned - though I'm not entirely clear or sure about that. 我没有直接在原始(工作)版本中直接发送mapView:rendererForOverlay消息,但是从调试器开始,它似乎是由我的addOverlayTo:方法触发的 - 我想通过返回的对象 - 虽然我不完全清楚或确定关于那个。
This works: 这有效:
// ParkMapVC.h
#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>
#import "ParkMap.h"
#import "ParkMapVC.h"
@interface ParkMapVC : UIViewController <MKMapViewDelegate>{
}
@property (strong, nonatomic) IBOutlet MKMapView *hikeMap;
@property (weak, nonatomic) IBOutlet MKMapView *mapView;
@property (nonatomic, strong) ParkMap *park;
+ (ParkMapVC *) sharedParkMapVC;
- (void)addOverlayTo :(ParkMap*) thePark;
@end
#import "ParkMapVC.h"
#import "ParkMap.h"
#import "ParkMapOverlay.h"
#import "ParkMapOverlayView.h"
@interface ParkMapVC ()
@end
//*************
@implementation ParkMapVC
+ (ParkMapVC *) sharedParkMapVC {
static ParkMapVC *sharedParkMapVC;
@synchronized (self) {
if (!sharedParkMapVC) {
sharedParkMapVC = [[ParkMapVC alloc] init ];
}
return sharedParkMapVC;
}
}
- (void)viewDidLoad
{
[super viewDidLoad];
self.park = [[ParkMap alloc] initWithFilename:@"EdgewoodVer2"]; // plist
// define region for apple map
self.mapView.region = [self.park defineMapRegion:self.park];
[self addOverlayTo:_park];
}
#pragma mark - Add methods
- (void)addOverlayTo :(ParkMap*) thePark{
ParkMapOverlay *overlay = [[ParkMapOverlay alloc]
initWithPark:self.park];
[self.mapView addOverlay:overlay];
}
#pragma mark - Map View delegate
// This should go to ParkMapOverlay 8.5.15
- (MKOverlayRenderer *)mapView:(MKMapView *)mapView rendererForOverlay:(id<MKOverlay>)overlay {
UIImage *overlayEdgewoodImage = [UIImage
imageNamed:@"EDGEoverlay_park_Cropped"];
ParkMapOverlayView *overlayView = [[ParkMapOverlayView alloc] initWithOverlay:overlay overlayImage:overlayEdgewoodImage];
return overlayView;
}
@end
What does not work : 什么行不通:
At this point - I moved the two methods - addOverlayTo: and mapView:rendererForOverlay- out to the class "ParkMapOverlay". 此时 - 我将两个方法 - addOverlayTo:和mapView:rendererForOverlay- out移动到类“ParkMapOverlay”。 I changed the way I was messaging addOverlayTo and it does execute from within the "ParkMapOverlay" class.
我改变了我的消息传递方式addOverlayTo ,它确实从“ParkMapOverlay”类中执行 。 However, based on debugger breakpoints, I can see that the mapView:rendererForOverlay method is not messaged , and indeed the overlay is not rendered.
但是,根据调试器断点,我可以看到mapView:rendererForOverlay方法没有消息 ,实际上覆盖层没有呈现。 I just see my apple map displayed in the view.
我只是看到我的苹果地图显示在视图中。
Here is the code: //Within ParkMapVC I altered overlay to message the new class ParkMapOverlay 这是代码://在ParkMapVC中我改变了覆盖层以消息新类ParkMapOverlay
[super viewDidLoad];
self.park = [[ParkMap alloc] initWithFilename:@"EdgewoodVer2"];
ParkMapOverlay *theOverlay = [[ParkMapOverlay alloc]init];
self.mapView.region = [self.park defineMapRegion:self.park];
self.mapView = [theOverlay addOverlayTo:_park ];
// Then I commented out the original two methods, moving the code to ParkMapOverlay
// ParkMapOverlay.h
#import <Foundation/Foundation.h>
#import <MapKit/MapKit.h>
@class ParkMap;
@interface ParkMapOverlay : NSObject <MKOverlay, MKMapViewDelegate>
- (instancetype)initWithPark:(ParkMap *)park;
- (MKMapView *)addOverlayTo :(ParkMap*) thePark;
@end
// ParkMapOverlay.m
#import "ParkMapOverlay.h"
#import "ParkMapOverlayView.h"
#import "ParkMap.h"
@implementation ParkMapOverlay
@synthesize coordinate;
@synthesize boundingMapRect;
- (instancetype)initWithPark:(ParkMap *)park {
self = [super init];
if (self) {
boundingMapRect = park.overlayBoundingMapRect;
coordinate = park.midCoordinate;
}
return self;
}
- (MKMapView *)addOverlayTo :(ParkMap*) thePark
{
ParkMapOverlay *overlay = [[ParkMapOverlay alloc] initWithPark:thePark];
MKMapView *mapView = [[MKMapView alloc] init];
[mapView addOverlay:overlay];
return mapView;
}
#pragma mark - Map View delegate
- (MKOverlayRenderer *)mapView:(MKMapView *)mapView rendererForOverlay:(id<MKOverlay>)overlay {
UIImage *overlayEdgewoodImage = [UIImage
imageNamed:@"EDGEoverlay_park_Cropped"];
ParkMapOverlayView *overlayView = [[ParkMapOverlayView alloc] initWithOverlay:overlay overlayImage:overlayEdgewoodImage];
return overlayView;
}
@end
What I wonder about - 我想知道的是什么 -
Thank you. 谢谢。 LRS
LRS
mapView:rendererForOverlay:
is a method of <MKMapViewDelegate>
protocol. mapView:rendererForOverlay:
是<MKMapViewDelegate>
协议的方法。
In your new addOverlayTo:
method you are initializing new MKMapView object but are not setting your ParkMapOverlay object as that map view's delegate. 在新的
addOverlayTo:
方法中,您正在初始化新的MKMapView对象,但未将ParkMapOverlay对象设置为该地图视图的委托。 This is why mapView:rendererForOverlay:
is not called. 这就是为什么不调用
mapView:rendererForOverlay:
原因。
Try to set it like mapView.delegate = self
. 尝试将其设置为
mapView.delegate = self
。
Also be careful with memory management: MKMapView's delegate
is a weak property ie it does not retain its delegate so you must be sure to keep your ParkMapOverlay object retained. 还要注意内存管理:MKMapView的
delegate
是一个弱属性,即它不保留其委托,所以你必须确保保留你的ParkMapOverlay对象。
Currently retain should happen correctly because you have both overlay functionality and mapView:rendererForOverlay:
method in one class so that adding that class as overlay via -[MKMapView addOverlay:]
ensures that object is retained but that is a side-effect of your design so be aware of it. 当前保留应该正确发生,因为你在一个类中同时具有覆盖功能和
mapView:rendererForOverlay:
方法,以便通过-[MKMapView addOverlay:]
将该类添加为覆盖,确保保留对象,但这是你设计的副作用,所以要意识到这一点。
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