Question

这是代码，它一切正常，但每次我点击“获取我的位置”按钮它会更新位置两次，我找不到原因，任何想法？我从下面删除了很多代码，它仍然这样做，所以我知道它在这个部分的某个地方。感谢。

.h文件：

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

@interface ViewController : UIViewController
@property (weak, nonatomic) IBOutlet UILabel *LatitudeLabel;
@property (weak, nonatomic) IBOutlet UILabel *LongitudeLabel;
@property (weak, nonatomic) IBOutlet UILabel *GPSAccuracyLabel;
@property (weak, nonatomic) IBOutlet UILabel *AltitudeLabel;
@property (weak, nonatomic) IBOutlet UILabel *VerticalAccuracyLabel;

- (IBAction)getCurrentLocation:(id)sender;
@end

@interface MyLocationViewController : UIViewController <CLLocationManagerDelegate>
@end

.m文件：

#import "ViewController.h"

@interface ViewController ()
@end

@implementation ViewController {
CLLocationManager *locationManager;
}

- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
locationManager = [[CLLocationManager alloc] init];
}

- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

- (IBAction)getCurrentLocation:(id)sender {
locationManager.delegate = (id)self;
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
[locationManager startUpdatingLocation];
}

#pragma mark - CLLocationManagerDelegate

- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error
{
NSLog(@"didFailWithError: %@", error); UIAlertView *errorAlert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"Failed to Get Your Location" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil]; [errorAlert show];
}

- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
NSLog(@"Location updated: %@", newLocation);
CLLocation *currentLocation = newLocation;

if (currentLocation != nil) {
    _LatitudeLabel.text = [NSString stringWithFormat:@"%.8f", currentLocation.coordinate.latitude];
    _LongitudeLabel.text = [NSString stringWithFormat:@"%.6f", currentLocation.coordinate.longitude];
    _GPSAccuracyLabel.text = [NSString stringWithFormat:@"%.2f", currentLocation.horizontalAccuracy];
    _AltitudeLabel.text = [NSString stringWithFormat:@"%.2f", currentLocation.altitude];
    _VerticalAccuracyLabel.text = [NSString stringWithFormat:@"%.2f", currentLocation.verticalAccuracy];
}

每次按下按钮时

控制台输出：

2014-11-22 23:49:37.539 MyLocationDemo[914:60b] Location updated: <+10.16863927,+124.75859298> +/- 10.00m (speed 0.00 mps / course -1.00) @ 22/11/14 11:49:37 pm Philippine Standard Time

2014-11-22 23:49:37.545 MyLocationDemo[914:60b] Location updated: <+10.16863927,+124.75859298> +/- 10.00m (speed 0.00 mps / course -1.00) @ 22/11/14 11:49:37 pm Philippine Standard Time

Answer 1

在快速浏览Apple的文档后，我注意到您使用的委托方法- locationManager:didUpdateToLocation:fromLocation:自iOS 6以来已被弃用。
相反，您应该使用- locationManager:didUpdateLocations:。

尝试使用下面的代码替换您的代码，看看它是否有任何区别：

编辑 - 我编辑了下面的代码来处理你得到的双重电话从上面的帖子中我发现它们几乎是同时发生的，所以基本上我们会检查自上次通话以来是否至少已经过了1秒。
可能有更好的方法来做到这一点，但这只是我的头脑... ... Haven在Xcode中检查了它，但是，如果我还没有写错字或其他内容，它应该可以正常工作。

// ViewController.m  
@interface ViewController ()  
@property (nonatomic, strong) NSDate *lastUpdateTime;  // Create a property  
@end                                                   // to hold current time  

- (void)viewDidLoad {  
    [super viewDidLoad];  
    self.lastUpdateTime = [NSDate date];  // In viewDidLoad, 'initialize' it  
                                          // to get the current time  
}  

- (void)locationManager:(CLLocationManager *)manager
 didUpdateLocations:(NSArray *)locations  
{  
    NSTimeInterval passedTime = -[self.lastUpdateTime timeIntervalSinceNow];  
    // Here we are checking how much seconds have passed since our lastUpdateTime  
    // Since lastUpdateTime is in the past, the result will be negative, therefore  
    // the minus sign, so we'll get a positive number  

    if(passedTime < 1) {  
        return;  
    }  // Now we check if less than one second have passed. If so, the whole method  
       // will return. If not, it will just continue executing

    CLLocation *currentLocation = [locations lastObject];  
    self.lastUpdateTime = [NSDate date];  // Don't forget to update the lastUpdateTime  
                                          // To hold the new update time

    if (currentLocation != nil) {  
        NSLog(@"Location updated: %@", currentLocation);
        _LatitudeLabel.text = [NSString stringWithFormat:@"%.8f", currentLocation.coordinate.latitude];  
        _LongitudeLabel.text = [NSString stringWithFormat:@"%.6f", currentLocation.coordinate.longitude];  
        _GPSAccuracyLabel.text = [NSString stringWithFormat:@"%.2f", currentLocation.horizontalAccuracy];  
        _AltitudeLabel.text = [NSString stringWithFormat:@"%.2f", currentLocation.altitude];  
        _VerticalAccuracyLabel.text = [NSString stringWithFormat:@"%.2f", currentLocation.verticalAccuracy];  
    }  
}

Answer 2

@ AMI289，你的想法奏效了，不再双重打电话了。

我在这里发布了最终代码以防其他人，我刚刚添加了locationManager = [[CLLocationManager alloc] init];。

//  ViewController.m

#import "ViewController.h"
@interface ViewController ()
@property (nonatomic, strong) NSDate *lastUpdateTime; // create a property to hold current time.
@end

@implementation ViewController {
CLLocationManager *locationManager;
}

- (void)viewDidLoad {
[super viewDidLoad];
self.lastUpdateTime = [NSDate date];  // In viewDidLoad, 'initialize' it to get the current time
locationManager = [[CLLocationManager alloc] init];
}

- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

- (IBAction)getCurrentLocation:(id)sender {
locationManager.delegate = (id)self;
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
[locationManager startUpdatingLocation];
}
#pragma mark - CLLocationManagerDelegate

- (void)locationManager:(CLLocationManager *)manager
 didUpdateLocations:(NSArray *)locations
{
NSTimeInterval passedTime = -[self.lastUpdateTime timeIntervalSinceNow];
// Here we are checking how much seconds have passed since our lastUpdateTime
// Since lastUpdateTime is in the past, the result will be negative, therefore
// the minus sign, so we'll get a positive number

if(passedTime < 1) {
    return;
}  // Now we check if less than one second have passed. If so, the whole method
// will return. If not, it will just continue executing

CLLocation *currentLocation = [locations lastObject];
self.lastUpdateTime = [NSDate date];  // Don't forget to update the lastUpdateTime
// To hold the new update time

if (currentLocation != nil) {
    NSLog(@"Location updated: %@", currentLocation);
    _LatutideLabel.text = [NSString stringWithFormat:@"%.8f", currentLocation.coordinate.latitude];
    _LongitudeLabel.text = [NSString stringWithFormat:@"%.6f", currentLocation.coordinate.longitude];
    _GPSAccuracyLabel.text = [NSString stringWithFormat:@"%.2f", currentLocation.horizontalAccuracy];
    _AltitudeLabel.text = [NSString stringWithFormat:@"%.2f", currentLocation.altitude];
    _VerticalAccuracyLabel.text = [NSString stringWithFormat:@"%.2f", currentLocation.verticalAccuracy];
}
// Stop Location Manager
[locationManager stopUpdatingLocation];
}

@end

为什么此代码每次更新位置两次？

2 个答案: