Question

我正在尝试使用路径数据库中的纬度和经度来推送到地图应用，并将用户从当前位置引导到路径。 API采用JSON格式。这是我在模型类中的自定义init方法：

- (instancetype)initWithDictionary:(NSDictionary *)dict
{
    self = [super init];
    if (self) {
        self.latitude = dict[@"lat"];
        self.longitude = dict[@"lon"];
        self.name = dict[@"name"];
        self.city = dict[@"city"];
        self.state = dict[@"state"];
        self.country = dict[@"country"];
        self.described = dict[@"description"];
        self.directions = dict[@"directions"];
        self.activities = dict[@"activity_type_name"];

    }
    return self;
}

以下是该类的坐标属性：

@property (nonatomic, assign) NSNumber *latitude;
@property (nonatomic, assign) NSNumber *longitude;

当应用调用directToTrail方法时，应用程序崩溃，代码在coordinate.latitude分配处显示<Thread 1: EXC_BAD_ACCESS (code=EXC_1386_GPFLT)>。以下是我的自定义单元类中该方法的代码。

- (void)directToTrail:(Trail *)trail
{


    CLLocationCoordinate2D coordinate;
    coordinate.latitude = (CLLocationDegrees)[trail.latitude doubleValue];
    coordinate.longitude = (CLLocationDegrees)[trail.longitude doubleValue];


    MKPlacemark *endLocation = [[MKPlacemark alloc] initWithCoordinate:coordinate addressDictionary:nil];
    MKMapItem *endingItem = [[MKMapItem alloc] initWithPlacemark:endLocation];
    NSMutableDictionary *launchOptions = [NSMutableDictionary new];
    [launchOptions setObject:MKLaunchOptionsDirectionsModeDriving forKey:MKLaunchOptionsDirectionsModeKey];
    [endingItem openInMapsWithLaunchOptions:launchOptions];
}



    MKPlacemark *endLocation = [[MKPlacemark alloc]     initWithCoordinate:coordinate addressDictionary:nil];
    MKMapItem *endingItem = [[MKMapItem alloc] initWithPlacemark:endLocation];
    NSMutableDictionary *launchOptions = [NSMutableDictionary new];
    [launchOptions setObject:MKLaunchOptionsDirectionsModeDriving     forKey:MKLaunchOptionsDirectionsModeKey];
    [endingItem openInMapsWithLaunchOptions:launchOptions];
}

当我在控制台中打印出coordinate.latitude以查看其值时，我得到0并且对于coordinate.longitude：1。这些不是来自API的值。我是从API准确地获取其他数据。为什么坐标数不正确？

Answer 1

您是否尝试将两个属性声明为强？实际上NSNumber是一个指针！

尝试：

@property (nonatomic, strong) NSNumber *latitude;
@property (nonatomic, strong) NSNumber *longitude;

而不是：

@property (nonatomic, assign) NSNumber *latitude;
@property (nonatomic, assign) NSNumber *longitude;

说实话，在我看来，将两个属性定义为double或CLLocationDegrees（实际上是typedef double CLLocationDegrees;）

更好

@property (nonatomic, assign) double latitude;
@property (nonatomic, assign) double longitude;

或以更“紧凑”的方式：

@property (nonatomic,assign)CLLocationCoordinate2D coordinate;

coordinate.latitude错误<thread 1：=“”exc_bad_access =“”（code =“EXC_1386_GPFLT）”>

1 个答案: