NSArrayM在被枚举时发生了变异

Question

应用程序崩溃并显示错误：

*** Terminating app due to uncaught exception 'NSGenericException', reason: '*** Collection <__NSArrayM: 0x21481c10> was mutated while being enumerated.'

仅当我在加载注释时移动地图视图时，才会发生这种情况。如果我不触摸地图，则没有发生错误。

- (void) startloading
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0),
                   ^{
                       [self loadPList];
                   });
}

我的代码是：

- (void) loadPList
{
@autoreleasepool {
    NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    NSString *path = [[documentPaths lastObject] stringByAppendingPathComponent:@"test.plist"];
    NSDictionary *dict = [NSDictionary dictionaryWithContentsOfFile:path];
    NSMutableArray *annotations = [[NSMutableArray alloc]init];

            NSMutableArray * annotationsToRemove = [ mapView.annotations mutableCopy ] ;
            [ annotationsToRemove removeObject:mapView.userLocation ] ;
            [ mapView removeAnnotations:annotationsToRemove ] ;

        if ([[NSUserDefaults standardUserDefaults] boolForKey:@"blackKey"])
        {
            NSArray *ann = [dict objectForKey:@"Black"];
            for(int i = 0; i < [ann count]; i++) {
                NSString *coordinates = [[ann objectAtIndex:i] objectForKey:@"Coordinates"];
                double realLatitude = [[[coordinates componentsSeparatedByString:@","] objectAtIndex:1] doubleValue];
                double realLongitude = [[[coordinates componentsSeparatedByString:@","] objectAtIndex:0] doubleValue];
                MyAnnotation *myAnnotation = [[MyAnnotation alloc] init];
                CLLocationCoordinate2D theCoordinate;
                theCoordinate.latitude = realLatitude;
                theCoordinate.longitude = realLongitude;
                myAnnotation.coordinate=CLLocationCoordinate2DMake(realLatitude,realLongitude);        
                myAnnotation.title = [[ann objectAtIndex:i] objectForKey:@"Name"];
                myAnnotation.subtitle = [[ann objectAtIndex:i] objectForKey:@"Address"];
                myAnnotation.icon = [[ann objectAtIndex:0] objectForKey:@"Icon"];
                [mapView addAnnotation:myAnnotation]; // SIGNAL SIGABRT
                [annotations addObject:myAnnotation];

            }
        }   

        if ([[NSUserDefaults standardUserDefaults] boolForKey:@"blueyellowKey"])
        {
            NSArray *ann = [dict objectForKey:@"BlueYellow"];
            for(int i = 0; i < [ann count]; i++) {
                NSString *coordinates = [[ann objectAtIndex:i] objectForKey:@"Coordinates"];
                double realLatitude = [[[coordinates componentsSeparatedByString:@","] objectAtIndex:1] doubleValue];
                double realLongitude = [[[coordinates componentsSeparatedByString:@","] objectAtIndex:0] doubleValue];
                MyAnnotation *myAnnotation = [[MyAnnotation alloc] init];
                CLLocationCoordinate2D theCoordinate;
                theCoordinate.latitude = realLatitude;
                theCoordinate.longitude = realLongitude;
                myAnnotation.coordinate=CLLocationCoordinate2DMake(realLatitude,realLongitude);        
                myAnnotation.title = [[ann objectAtIndex:i] objectForKey:@"Name"];
                myAnnotation.subtitle = [[ann objectAtIndex:i] objectForKey:@"Address"];
                myAnnotation.icon = [[ann objectAtIndex:0] objectForKey:@"Icon"];
                [mapView addAnnotation:myAnnotation];
                [annotations addObject:myAnnotation];              
            }
        }   

   }
}

Answer 1

我认为您应该将loadPlist方法更改为此方法，然后只需调用[self loadPlist]即可调用它：

- (void) loadPList
{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
        NSString *path = [[documentPaths lastObject] stringByAppendingPathComponent:@"test.plist"];
        NSDictionary *dict = [NSDictionary dictionaryWithContentsOfFile:path];
        //ALL THIS CODE FROM HERE ON OUT IS NOT THREAD SAFE! YOU ARE ACCESSING THE UI AND MUST PERFORM IT ON THE MAIN THREAD!
        dispatch_async(dispatch_get_main_queue(), ^{
            NSMutableArray *annotations = [[NSMutableArray alloc]init];
            NSMutableArray * annotationsToRemove = [ mapView.annotations mutableCopy ] ;
            [ annotationsToRemove removeObject:mapView.userLocation ] ;
            [ mapView removeAnnotations:annotationsToRemove ] ;

            if ([[NSUserDefaults standardUserDefaults] boolForKey:@"blackKey"])
            {
                NSArray *ann = [dict objectForKey:@"Black"];
                for(int i = 0; i < [ann count]; i++) {
                    NSString *coordinates = [[ann objectAtIndex:i] objectForKey:@"Coordinates"];
                    double realLatitude = [[[coordinates componentsSeparatedByString:@","] objectAtIndex:1] doubleValue];
                    double realLongitude = [[[coordinates componentsSeparatedByString:@","] objectAtIndex:0] doubleValue];
                    MyAnnotation *myAnnotation = [[MyAnnotation alloc] init];
                    CLLocationCoordinate2D theCoordinate;
                    theCoordinate.latitude = realLatitude;
                    theCoordinate.longitude = realLongitude;
                    myAnnotation.coordinate=CLLocationCoordinate2DMake(realLatitude,realLongitude);        
                    myAnnotation.title = [[ann objectAtIndex:i] objectForKey:@"Name"];
                    myAnnotation.subtitle = [[ann objectAtIndex:i] objectForKey:@"Address"];
                    myAnnotation.icon = [[ann objectAtIndex:0] objectForKey:@"Icon"];
                    [mapView addAnnotation:myAnnotation]; // SIGNAL SIGABRT
                    [annotations addObject:myAnnotation];
                }
            }   
            if ([[NSUserDefaults standardUserDefaults] boolForKey:@"blueyellowKey"])
            {
                NSArray *ann = [dict objectForKey:@"BlueYellow"];
                for(int i = 0; i < [ann count]; i++) 
                {
                    NSString *coordinates = [[ann objectAtIndex:i] objectForKey:@"Coordinates"];
                    double realLatitude = [[[coordinates componentsSeparatedByString:@","] objectAtIndex:1] doubleValue];
                    double realLongitude = [[[coordinates componentsSeparatedByString:@","] objectAtIndex:0] doubleValue];
                    MyAnnotation *myAnnotation = [[MyAnnotation alloc] init];
                    CLLocationCoordinate2D theCoordinate;
                    theCoordinate.latitude = realLatitude;
                    theCoordinate.longitude = realLongitude;
                    myAnnotation.coordinate=CLLocationCoordinate2DMake(realLatitude,realLongitude);        
                    myAnnotation.title = [[ann objectAtIndex:i] objectForKey:@"Name"];
                    myAnnotation.subtitle = [[ann objectAtIndex:i] objectForKey:@"Address"];
                    myAnnotation.icon = [[ann objectAtIndex:0] objectForKey:@"Icon"];
                    [mapView addAnnotation:myAnnotation];
                    [annotations addObject:myAnnotation];              
                }
            }   
        }
    });
 }

这将在后台执行读取批注的 IO 工作，然后将 UI 工作传递回主线程。希望这有帮助！