iOS CLLocationManagerDelegate didUpdateToLocation 未被调用

Question

我正在创建一个使用核心位置的应用程序，这是我的代码:

.h :

#import <UIKit/UIKit.h>
#import <CoreLocation/CoreLocation.h>    
@interface ViewController : UIViewController
<CLLocationManagerDelegate>    
@property(strong,nonatomic) CLLocationManager *manager;    
@end

.m :

#import "ViewController.h"
#import <CoreLocation/CoreLocation.h>
@interface ViewController ()
@end
@implementation ViewController
@synthesize manager;
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}
- (void)viewDidLoad
{
    [super viewDidLoad];
    if (!self.manager)
    {
        self.manager=[CLLocationManager new];
    }
    self.manager.delegate = self;
    self.manager.desiredAccuracy = kCLLocationAccuracyBestForNavigation;
    [self.manager startUpdatingLocation];
}
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
    CLLocation * currentLocation = (CLLocation *)[locations lastObject];
    NSLog(@"Location: %@", currentLocation);
    if (currentLocation != nil)
    {
        NSLog([NSString stringWithFormat:@"%.8f", currentLocation.coordinate.latitude]);
        NSLog([NSString stringWithFormat:@"%.8f", currentLocation.coordinate.longitude]);
    }
}
@end

问题是 didUpdateToLocation 没有被调用。我尝试在其中放置一个断点，但什么也没发生。

Answer 1

要使 iOS 位置跟踪正常工作，先决条件如下，顺序也很重要:

1. 将您的类定义为 CLLocationManagerDelegate。
2. 实例化 CLLocationManager 实例。
3. 将其delegate 设置为self。
4. 设置它的各种属性(准确度等)
5. 在需要时调用 [CLLocationManagerDelegate startUpdatingLocation]。
6. 在您的委托(delegate)方法 didUpdateLocations 中监听位置更新，该方法在指定为 CLLocationManagerDelegate 的类中实现。

对于您的代码，以下是您需要更正的地方:

-(IBAction)submit
{   
    [self.manager startUpdatingLocation];  
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    if (!self.manager)
    {
        self.manager=[CLLocationManager new];
    }
    self.manager.delegate = self;
    self.manager.desiredAccuracy = kCLLocationAccuracyBestForNavigation;     
}

简而言之，在告诉它开始更新位置之前，您需要实例化它并正确设置它的属性。目前你正在以相反的方式进行。

更新

此外，您的委托(delegate)方法 didUpdateToLocation 自 iOS 6 起已弃用。您必须将其替换为 newer method ，像这样:

- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{    
    CLLocation * currentLocation = (CLLocation *)[locations lastObject];
    NSLog(@"Location: %@", currentLocation);
    if (currentLocation != nil) 
    {
        self.latitude.text = [NSString stringWithFormat:@"%.8f", currentLocation.coordinate.latitude];
        self.longitude.text = [NSString stringWithFormat:@"%.8f", currentLocation.coordinate.longitude];
    }
}