Question

过去几天我一直在敲打着脑袋，开始慢慢地消耗我。我正在尝试制作CLLocationManager Singleton，因为我需要一个位置用于我的应用程序的其他两个组件。但是，当我设置currentLocation属性时，我不断获得EXC_BAD_ACCESS。当我确实通过它时，我在main.m上获得了一个SIGABRT哦，最重要的是，什么时候过去，以及SIGABRT我被告知我的KVO消息已收到但未处理，我不知道是什么这意味着。

在使用KVO之前，我应该了解任何帮助以及KVO资源和/或基本资源

LocationFetch.h

@interface LocationFetch : NSObject <CLLocationManagerDelegate>

+(LocationFetch *) sharedInstance;

@property (nonatomic,strong) CLLocationManager *locationManager;
@property (nonatomic, strong) CLLocation *currentLocation;

-(void)startingUpdatingLocation;
-(void)stopUpdatingLocation;

@end

LocationFetch.m

#import "LocationFetch.h"

@implementation LocationFetch

@synthesize locationManager, currentLocation;

+(LocationFetch *) sharedInstance
{
    static LocationFetch *instance;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        instance = [[self alloc]init];
        });
    return instance;
}
- (id)init
{
    self = [super init];
    if(self)
    {

        self.locationManager = [[CLLocationManager alloc]init];
        self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
        self.locationManager.distanceFilter = 100;
        self.locationManager.delegate = self;
        //Request Authorization
        if ([self.locationManager respondsToSelector:@selector(requestWhenInUseAuthorization)])
        {
            [self.locationManager requestWhenInUseAuthorization];
        }
    }
    return self;
}
- (void)startingUpdatingLocation
{
    [self.locationManager startUpdatingLocation];
    NSLog(@"Starting Location Updates");
}
-(void)stopUpdatingLocation
{
    [self.locationManager stopUpdatingLocation];
     NSLog(@"Stopping Location Updates");
}
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error
{
    NSLog(@"Location updates failed with %@", error);
}
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray<CLLocation *> *)locations
{
    CLLocation *location = [locations lastObject];
    NSLog(@"LocationFetch sharedInstance: Latitude %+.6f, Longitude %+.6f\n",
          location.coordinate.latitude,
          location.coordinate.longitude);
    self.currentLocation = location;
}



@end

WeatherFetch.m的一部分（这是注册观察者的地方）

-(id)init
{
    self = [super init];
    if(self)
    {
        [[LocationFetch sharedInstance] addObserver:self forKeyPath:@"currentLocation" options:NSKeyValueObservingOptionNew context:nil];
    }
    return self;
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object  

change:(NSDictionary *)change context:(void *)context
{
    if([keyPath isEqualToString:@"currentLocation"]) {
        [self setWeatherLocation];
        [self sendWeatherRequest];
        NSLog(@"Observer has received message");
        [self removeObserver:self forKeyPath:@"currentLocation" context:nil];
    }
}

编辑：这是我关注Singleton的指南：http://derpturkey.com/cllocationmanager-singleton/

另一个编辑：好的，我通过删除CLLocationManager和CLLocation的强和非原子的属性属性来解决EXC_BAD_ACCESS错误，但现在SIGABRT现在是一个更关键的问题，这里是异常的调试输出。从好的方面来看，KVO现在似乎已经通知，只是不明白错误“消息已收到但未处理”

2016-06-24 21:25:51.111 TrafficAlarmClock[1504:18554] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '(
    "<CALayer: 0x7f95a043eb00>"
): An -observeValueForKeyPath:ofObject:change:context: message was received but not handled.
Key path: currentLocation
Observed object: <LocationFetch: 0x7f95a040c5a0>
Change: {
    kind = 1;
    new = "<+40.75921100,-73.98463800> +/- 5.00m (speed -1.00 mps / course -1.00) @ 6/24/16, 9:25:50 PM Eastern Daylight Time";
}
Context: 0x1050f7c08'
*** First throw call stack:
(
    0   CoreFoundation                      0x0000000105f97d85 __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x0000000105682deb objc_exception_throw + 48
    2   CoreFoundation                      0x0000000105f97cbd +[NSException raise:format:] + 205
    3   Foundation                          0x00000001052e71ae -[NSObject(NSKeyValueObserving) observeValueForKeyPath:ofObject:change:context:] + 168
    4   Foundation                          0x0000000105213cad NSKeyValueNotifyObserver + 347
    5   Foundation                          0x0000000105212f39 NSKeyValueDidChange + 466
    6   Foundation                          0x00000001052e7fff -[NSObject(NSKeyValueObservingPrivate) _changeValueForKeys:count:maybeOldValuesDict:usingBlock:] + 912
    7   Foundation                          0x0000000105210804 -[NSObject(NSKeyValueObservingPrivate) _changeValueForKey:key:key:usingBlock:] + 60
    8   Foundation                          0x000000010526ea9b _NSSetObjectValueAndNotify + 261
    9   TrafficAlarmClock                   0x00000001050f2143 -[LocationFetch locationManager:didUpdateLocations:] + 227
    10  CoreLocation                        0x0000000105192418 CLClientGetCapabilities + 20974
    11  CoreLocation                        0x000000010518e823 CLClientGetCapabilities + 5625
    12  CoreLocation                        0x00000001051892dd CLClientInvalidate + 923
    13  CoreFoundation                      0x0000000105ebd2ec __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    14  CoreFoundation                      0x0000000105eb2f75 __CFRunLoopDoBlocks + 341
    15  CoreFoundation                      0x0000000105eb2d28 __CFRunLoopRun + 2472
    16  CoreFoundation                      0x0000000105eb20f8 CFRunLoopRunSpecific + 488
    17  GraphicsServices                    0x0000000108660ad2 GSEventRunModal + 161
    18  UIKit                               0x000000010634ef09 UIApplicationMain + 171
    19  TrafficAlarmClock                   0x00000001050f1b6f main + 111
    20  libdyld.dylib                       0x0000000108fd192d start + 1
    21  ???                                 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

另一个编辑：好的，我想我完全不明白将观察者等等放在我的应用程序中的位置。我现在拥有它，以便我的viewcontroller是订阅者，现在我越来越接近我想要的行为。如果有人对MVC和MVC / iOS开发的软件设计有很好的指导，请分享。也欢迎预订建议。

Answer 1

无法分辨导致KVO错误的原因是因为缺乏精确性而只是告诉我们在类似案例中做了什么

这就是我们分配LocationHelper实例的方式：

- (id)init { self = [super init];

if (!self) {
    return self;
}

// Check if the service is available
if ([CLLocationManager locationServicesEnabled])
{
    // Init the location manager
    self.locationManager = [[CLLocationManager alloc] init];
    self.locationManager.delegate = self;
    self.locationManager.pausesLocationUpdatesAutomatically = YES;
    self.locationManager.desiredAccuracy = LOCATION_ACCURACY_IN_METER;
}

return self;}

然后我不明白为什么你不使用：

- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations

然后使用manager.location从这里调用setWeatherLocation或sendWeatherRequest。

如果不符合您的预期，请详细说明您的崩溃

Answer 2

我建议不要创建一个单例，只需在app delegate上创建一个实例，然后在appdelegate上保存用户坐标，这样你就可以随时获得用户精确的位置，也许你需要调整它的准确性，这样它就不会这样做。 t排水电池和appdelegate已经是一个单一的:)）

如果你想做单打与KVO的崩溃是因为这一行：

[[LocationFetch sharedInstance] addObserver:self forKeyPath:@"currentLocation" options:NSKeyValueObservingOptionNew context:nil];

当您添加观察者时，您必须自己将其删除，请在单例文件中尝试：

- (void)dealloc {
 [[LocationFetch sharedInstance] removeObserver:self forKeyPath:@"currentLocation"];
}

我不是百分百肯定从一个单独的类中删除观察者。代码看起来很奇怪，但我认为它会起作用

设置属性导致EXC_BAD_ACCESS崩溃（CLLocationManager Singleton）

2 个答案: