EXC_BAD_ACCESS（code = 1）Xcode中的錯誤

Question

我知道這個錯誤與內存管理有關，但我必須承認我很難過！ 在目標c中編程大約3周，所有這些管理內存的東西都令人困惑！ 基本上發生的是我在tableview中有這個mapview。 單擊后退按鈕離開mapview並返回主菜單時，我得到上面的錯誤。 這是Header文件中的代碼

#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>

@interface MapViewController : UIViewController <MKMapViewDelegate> {

    IBOutlet MKMapView* mapView;
    BOOL locate;

}

@property (nonatomic, retain) IBOutlet MKMapView* mapView;

@end

和實施文件

#import "MapViewController.h"

@implementation MapViewController

@synthesize mapView;

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
    [super viewDidLoad];

    mapView = [[MKMapView alloc] initWithFrame:self.view.frame];
    mapView.delegate=self;
    mapView.showsUserLocation = YES;

    [self.view addSubview:mapView];

    [self.mapView.userLocation addObserver:self
                                forKeyPath:@"location"
                                   options:(NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOld)
                                   context:nil];
    locate = YES;

}

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{

    if (locate == YES) {
    MKCoordinateRegion region;
    region.center = self.mapView.userLocation.coordinate;

    MKCoordinateSpan span;
    span.latitudeDelta  = 0.1; 
    span.longitudeDelta = 0.1;
    region.span = span;

    [self.mapView setRegion:region animated:YES];
        locate = NO;
    }

}

- (void)didReceiveMemoryWarning {
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

    // Release any cached data, images, etc that aren't in use.
}
- (void)dealloc {
    [super dealloc];
    [mapView release];
    [self.mapView.userLocation removeObserver:self forKeyPath:@"location"];
    [self.mapView removeFromSuperview];
    self.mapView = nil;
}

@end

有人可以為我揭開光明嗎？ :)

Answer 1

[super dealloc]; 必須是dealloc的最后一次調用

也是在[mapView release]; mapView可能已經消失了。

嘗試

- (void)dealloc {

    [self.mapView.userLocation removeObserver:self forKeyPath:@"location"];
    [self.mapView removeFromSuperview];
    [mapView release];
    self.mapView = nil; 
    [super dealloc];  // at this point self — that is the same object as super — is not existent anymore
}

Answer 2

此錯誤也可能由不兼容的API引起（例如，您為iOS 6.0構建，但使用僅在iOS> = 8.2中引入的方法）