CLLocationManager 委托在初始化后不工作

Question

我正在尝试让 iphone 的指南针使用 rhomobile 框架工作。 我已经完成了 rhomobile 部分，创建了一个在 iphone 上调用本机方法的工作包装器，但我无法让事件正常工作。

Locationmanager.h

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

@interface locationController : NSObject <CLLocationManagerDelegate> 
{
    CLLocationManager *locationManager;
}
@property (strong, nonatomic) CLLocationManager *locationManager;

- (id)init;
- (void)dealloc;

@end

Locationmanager.m

#import "Locationmanager.h"

#include "ruby/ext/rho/rhoruby.h"

//store the values
double gx, gy, gz, gth;

//init location
locationController *lc;
@implementation locationController

@synthesize locationManager;

- (id)init {
if (self = [super init]) {
    self.locationManager = [[CLLocationManager alloc] init];

    NSLog(@"%@", [CLLocationManager headingAvailable]? @"\n\nHeading available!\n" : @"\n\nNo heading..\n");
    NSLog(@"%@", [CLLocationManager locationServicesEnabled]? @"\n\nLocation available!\n" : @"\n\nNo location..\n");

    // check if the hardware has a compass
    if ([CLLocationManager headingAvailable] == NO) {
        // No compass is available. This application cannot function without a compass, 
        // so a dialog will be displayed and no magnetic data will be measured.
        locationManager = nil;
        UIAlertView *noCompassAlert = [[UIAlertView alloc] initWithTitle:@"No Compass!" message:@"This device does not have the ability to measure magnetic fields." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [noCompassAlert show];
        [noCompassAlert release];
        NSLog(@"\n***** ERROR *****\n No compass found !!!");
    } else {
        // setup delegate callbacks
        locationManager.delegate = self;

        // heading service configuration
        locationManager.headingFilter = kCLHeadingFilterNone;

        // location service configuration
        locationManager.distanceFilter = kCLDistanceFilterNone;
        locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters;

        //start location services
        [locationManager startUpdatingLocation];

        // start the compass
        [locationManager startUpdatingHeading];

    }
return self;
}
}
- (void)dealloc {    
    [super dealloc];
    // Stop the compass
    [locationManager stopUpdatingHeading];
    [locationManager release];
}

// This delegate method is invoked when the location manager has heading data.
- (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)heading {
    NSLog(@"\n\n***** New magnetic heading *****\n %f\n", heading.magneticHeading);
    NSLog(@"\n\n***** New true heading *****\n %f\n", heading.trueHeading);
    gx = heading.x;
    gy = heading.y;
    gz = heading.z;
    gth = heading.trueHeading;
}

// This delegate method is invoked when the location managed encounters an error condition.
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error {
    if ([error code] == kCLErrorDenied) {
        // This error indicates that the user has denied the application's request to use location services.
        NSLog(@"\n ***** ERROR *****\n Location not allowed!");
        [locationManager stopUpdatingHeading];
    } else if ([error code] == kCLErrorHeadingFailure) {
        NSLog(@"\n ***** ERROR *****\n Magnetic interference or something!");
    }
}

@end

//ruby wrappers
void locationmanager_init(void) {
   // make sure we can only start this method once
   static bool started = false;
   if(!started) {
       // Initialize the Objective C accelerometer class.
       lc = [[locationController alloc] init];
       started = true;
   }

}

void locationmanager_get_heading(double *x, double *y, double *z, double *th) {
    NSLog(@"\n ***** DEBUGGER *****\n Getting heading  x: %f, y: %f, z: %f, heading: %f", gx, gy, gz, gth);
    *x = gx;
    *y = gy;
    *z = gz;
    *th = gth;
}

我在带有 iOS 5.1 的 iphone 4 上运行代码，在控制台中我可以看到 init 的调试消息，但我从未看到 didUpdateHeading 委托的调试消息。有人知道我在这里错过了什么吗？

更新

我认为我需要在后台线程中运行我的代码才能使其正常工作。当前 locationmanager_init 初始化 + 离开代码，因此它不活动并且不会触发事件。 任何人有一个简单的解决方案在后台初始化它以保持它的活跃？

更新 2

返回 id，使用 self = [super init] 仍然没有修复:(

GitHub code 用 locationmanager_init 初始化，用 locationmanager_get_heading 检索数据

Answer 1

您必须在主线程上初始化CLLocationManager，检查此 SO here，或从具有活动运行循环的线程运行它，检查此 SO here，来自 Apple 文档：

Configuration of your location manager object must always occur on a thread with 
an active run loop, such as your application’s main thread.

确保您的locationController 和其中的CCLocationManager 在初始化之后仍然存在，检查here。我在这里可能错了，但是从您的 Github 代码来看，*lc 变量似乎正在自动释放池中释放。尝试给它一个额外的保留。

lc = [[[locationController alloc] init] retain];

我想这是你的问题的原因。如果对象被释放，您将不会得到任何更新。

与问题无关，但：

你应该最后而不是第一个打电话给[super dealloc]，检查这个SO here

将 return 语句放在 init 方法中最后一个括号之前，而不是在倒数第二个之前。

        ...
        // start the compass
        [locationManager startUpdatingHeading];

        }
    }
    return self;
}

Answer 2

- (void)locationManager:(CLLocationManager *)manager 
didUpdateHeading:(CLHeading *)heading;
- (void)locationManager:(CLLocationManager *)manager 
didFailWithError:(NSError *)error;

这些是您的实例方法，而不是委托方法。

检查 https://developer.apple.com/library/mac/#documentation/CoreLocation/Reference/CLLocationManagerDelegate_Protocol/CLLocationManagerDelegate/CLLocationManagerDelegate.html

Answer 3

这可能不是整体问题的解决方案，但您的 init 方法缺少返回语句：

- (id)init {
  if (self = [super init]) {
    // do your setup here
  }

  return self;
}