iphone - 在iPad上制作一个指南针应用程序

Question

我想制作一个指南针应用程序来指定地理方向(北、东、西、南)，

所以我在我的应用程序中使用了 CoreLocation 框架。我在很多论坛中发现，当这个函数 [locationManager startUpdatingHeading]; 调用时，它会自动调用该函数: -(void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading

但是在我的应用程序中，第二个函数不会自动调用，所以我无法制作我的应用程序，请帮助我......我的代码如下:

-(void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading
{
    NSLog(@"New magnetic heading: %f", newHeading.magneticHeading);
    NSLog(@"New true heading: %f", newHeading.trueHeading);
    NSString *headingstring = [[NSString alloc] initWithFormat:@"%f",newHeading.trueHeading];
    trueHeading.text = headingstring;
    [headingstring release];

    NSString *magneticstring = [[NSString alloc] initWithFormat:@"%f",newHeading.magneticHeading];
    magneticHeading.text = magneticstring;
    [magneticstring release];
}

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

    [super viewDidLoad];

    locationManager=[[CLLocationManager alloc] init];
    locationManager.desiredAccuracy = kCLLocationAccuracyBest;
    locationManager.delegate=self;
    //Start the compass updates.
    if (CLLocationManager.headingAvailable ) {     
        [locationManager startUpdatingHeading];
    }
    else {
        NSLog(@"No Heading Available: ");
        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];
    }
}

请帮助我

斯雷库玛·卡拉里卡尔印度

Answer 1

iOS 模拟器上没有可用的标题(并且您的代码提供了适当的警报 View )。

在设备上，此代码运行良好。

(在模拟器和设备上测试了您的代码)