Question

当我在iOS 6中加载地图视图时遇到问题。但是它与以前的操作系统版本一起工作了100％。

以下是代码：

//.h file
MKMapView *galleryListMap; //map view
NSMutableArray *copyOfAllRecords; //array with locations

这是我的.m文件中的代码结构。我已合成变量并以dealloc方法释放它们。

//this will runs in a background thread and populateMap method will make all the   annotations
//[self performSelectorInBackground:@selector(populateMap) withObject:nil];

//here is populateMap method
-(void)populateMap{

NSAutoreleasePool *pool = [[NSAutoreleasePool alloc]init]; 
NSArray *existingpoints = galleryListMap.annotations;

//removes alll the existing points
[galleryListMap removeAnnotations:existingpoints];



//assign point to map view
for(int i = 0; i < [copyOfAllRecords count]; i++) {

     Gallery  *gallery = (Gallery *)[copyOfAllRecords objectAtIndex:i];//array which has the elements

     //create location based on the latitude and longtitude
     CGFloat latDelta = gallery.latitude;
     CGFloat longDelta = gallery.longitude;
     CLLocationCoordinate2D newCoord = {latDelta, longDelta};

      //adds the notations
     AddressAnnotation *addrAnnotation = [[[AddressAnnotation alloc] initWithCoordinate:newCoord]autorelease];
     //assing the location the map

    [addrAnnotation setId:i];
    [addrAnnotation setTitle:gallery.name];

    if([gallery.exhibition length]==0 && !gallery.isResturant){
        [addrAnnotation setSubtitle:@""];

    }else{
        [addrAnnotation setSubtitle:gallery.exhibition];
    }

    **//gives the exception on this line
    [galleryListMap addAnnotation:addrAnnotation];**

}

MKCoordinateRegion region;
MKCoordinateSpan span = MKCoordinateSpanMake(0.2, 0.2);
Gallery *lastGalleryItem = [copyOfAllRecords lastObject];
CLLocationCoordinate2D location = {lastGalleryItem.latitude, lastGalleryItem.longitude};

region.span=span;
region.center=location;

[galleryListMap setRegion:region animated:TRUE];
[galleryListMap regionThatFits:region];

galleryListMap.showsUserLocation = YES;

[pool release];

}

- (MKAnnotationView *) mapView:(MKMapView *)mkmapView viewForAnnotation:(AddressAnnotation *) annotation{


   static NSString *identifier = @"currentloc";

if([annotation isKindOfClass:[AddressAnnotation class]]){

    MKPinAnnotationView *annView = [[[MKPinAnnotationView alloc]initWithAnnotation:addAnnotation reuseIdentifier:identifier]autorelease];

    Gallery *galItem = (Gallery *)[copyOfAllRecords objectAtIndex:annotation.annotationId];

    CGRect viewFrame;
    UIView *myView;
    UIImage *tagImage;

     //checks whether the resturant or not
    if (galItem.isResturant) {

     viewFrame = CGRectMake( 0, 0, 41, 45 );
     myView = [[UIView alloc] initWithFrame:viewFrame];
     tagImage= [UIImage imageNamed:@"map_restaurant"];

    }else{

    viewFrame = CGRectMake( 0, 0, 41, 45 );
    myView = [[UIView alloc] initWithFrame:viewFrame];
    tagImage= [UIImage imageNamed:galItem.mapMarker];

    }


    UIImageView *tagImageView = [[UIImageView alloc] initWithImage:tagImage];
    [myView addSubview:tagImageView];
    [tagImageView release];


    UIGraphicsBeginImageContext(myView.bounds.size);
    [myView.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();



    [annView setImage:viewImage];
    [myView release];

    int recordCount =[copyOfAllRecords count];


    if (recordCount != 0 ) {
        UIButton *annotationButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
        [annotationButton addTarget:self action:@selector(showLinks:) forControlEvents:UIControlEventTouchUpInside];
        annotationButton.tag  = [annotation annotationId];
        annView.rightCalloutAccessoryView = annotationButton;
    }


    if([annotation annotationId]==recordCount-1){
        //hides loading screen
         //[HUD hide:YES];
         self.mapAlreadyLoaded = YES;

    }


    return annView;


}


return nil;

}

我得到的例外是：

*** Terminating app due to uncaught exception 'NSGenericException', 
reason: '*** Collection <__NSArrayM: 0x21683870> was mutated while being enumerated.'
*** First throw call stack:
(0x32dc62a3 0x3259897f 0x32dc5d85 0x37c4d33b 0x37c50373 0x86e63 0x37dcc67d 0x36e52311 0x36e521d8)

但如果我使用：

[self populateMap];
//[self performSelectorInBackground:@selector(populateMap) withObject:nil];

该应用程序运行正常。

知道为什么会这样吗？

Answer 1

这可能会发生多种原因 - 错误告诉您，在某些时候您（或基础iOS库）尝试枚举在该过程正在进行时更改的数组。

当你在主线程populateMap关闭而在你在辅助线程上调用时它工作的事实表明存在某种竞争条件。

请记住，并非所有UIKit都是线程安全的（大部分都不是） - 因此可能存在问题。您仍然在后台线程上添加注释到地图：

[galleryListMap addAnnotation:addrAnnotation];

...这也是崩溃发生的路线。按理说，当您向MapView添加注释时，它可能会迭代其所有当前注释以更新显示。因为你在后台线程中进行这些调用，这可能会带来很多问题。

相反，试试这个：

[galleryListMap performSelectorOnMainThread:@selector(addAnnotation:)
                                 withObject:addrAnnotation 
                               waitUntilDone:YES]

这将强制地图视图在主线程上添加注释。作为一般规则，UIKit中只有少数东西是线程安全的（Apple文档有完整列表）。

Mapview在iOS 6中崩溃

1 个答案: