所以我对此完全陌生。我正在关注当地的天气教程
它没有按应有的方式工作。当我点击 RUN 时，会弹出一个窗口，提示您是否要允许此应用访问位置管理器。但是消息在我有机会点击它之前就消失了，然后应用程序什么也不做。
下面是我的代码......经过研究，我发现了这个信息
虽然很难追踪，但解决方案非常简单。
经过反复试验，我发现当您第一次尝试访问应用程序中的任何位置服务时会弹出位置访问对话框，如果CLLocationManager之前释放该对象，该对话框会自行消失（无需任何用户交互）用户响应对话框。
我正在我的方法中创建一个CLLocationManager实例。viewDidLoad由于这是该方法的本地实例，因此该实例ARC在方法执行完成后被释放。一旦实例被释放，对话框就消失了。解决方案相当简单。将CLLocationManager实例从方法级变量更改为类级实例变量。现在CLLocationManager实例只有在类被卸载后才会被释放。
这可能是答案，但我不知道如何从方法级别更改为类级别变量。
有人可以协助将其更改为类级别变量吗？
这是我的代码
#import <Foundation/Foundation.h>
#import <CoreLocation/CoreLocation.h>
@protocol LocationGetterDelegate <NSObject>
@required
- (void) newPhysicalLocation:(CLLocation *)location;
@end
@interface LocationGetter : NSObject
<CLLocationManagerDelegate>{
CLLocationManager *locationManager;
id delegate;
}
-(void)startUpdates;
@property (nonatomic, retain) CLLocationManager *locationManager;
@property (nonatomic, retain) id delegate;
@end
#import "LocationGetter.h"
#import <CoreLocation/CoreLocation.h>
@implementation LocationGetter
@synthesize locationManager,delegate;
BOOL didUpdate = NO;
- (void) startUpdates{
NSLog(@"Starting Location Updates");
if (locationManager == nil)
locationManager = [[CLLocationManager alloc]init];
locationManager.delegate = self;
locationManager.desiredAccuracy = kCLLocationAccuracyKilometer;
[locationManager startUpdatingLocation];
}
- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"Your location could not be determined." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles: nil];
[alert show];
}
// Delegate method from the CLLocationManagerDelegate protocol.
- (void)locationManager:(CLLocationManager *)manage didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation
{
if (didUpdate)
return;
didUpdate = YES;
// Disable future updates to save power.
[locationManager stopUpdatingLocation];
// let our delegate know we're done
[delegate newPhysicalLocation:newLocation];
}
@end
#import <UIKit/UIKit.h>
#import "LocationGetter.h"
@class ViewController;
@interface AppDelegate : UIResponder
<UIApplicationDelegate, LocationGetterDelegate>
{
UIWindow *window;
ViewController *viewController;
CLLocation *lastKnownLocation;
}
@property (retain, nonatomic) UIWindow *window;
@property (retain, nonatomic) ViewController *viewController;
@property (nonatomic, retain) CLLocation *lastKnownLocation;
@end
#import "AppDelegate.h"
#import "ViewController.h"
#import "LocationGetter.h"
@implementation AppDelegate
@synthesize lastKnownLocation;
@synthesize viewController;
@synthesize window;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
// // Override point for customization after application launch.
// self.viewController = [[ViewController alloc] initWithNibName:@"ViewController" bundle:nil];
// self.window.rootViewController = self.viewController;
// [self.window makeKeyAndVisible];
UIActivityIndicatorView *spinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
spinner.center = CGPointMake(self.viewController.view.frame.size.width / 2, self.viewController.view.frame.size.height / 2);
[spinner startAnimating];
[viewController.view addSubview:spinner];
// get our physical location
LocationGetter *locationGetter = [[LocationGetter alloc] init];
locationGetter.delegate = self;
[locationGetter startUpdates];
// Add the view controller's view to the window and display.
[window addSubview:viewController.view];
[window makeKeyAndVisible];
return YES;
}
- (void)applicationWillResignActive:(UIApplication *)application
{
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}
- (void)applicationDidEnterBackground:(UIApplication *)application
{
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}
- (void)applicationWillEnterForeground:(UIApplication *)application
{
// Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
}
- (void)applicationDidBecomeActive:(UIApplication *)application
{
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}
- (void)applicationWillTerminate:(UIApplication *)application
{
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}
- (void)newPhysicalLocation:(CLLocation *)location {
// Store for later use
self.lastKnownLocation = location;
// Remove spinner from view
for (UIView *v in [self.viewController.view subviews])
{
if ([v class] == [UIActivityIndicatorView class])
{
[v removeFromSuperview];
break;
}
}
// Alert user
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Location Found" message:[NSString stringWithFormat:@"Found physical location. %f %f", self.lastKnownLocation.coordinate.latitude, self.lastKnownLocation.coordinate.longitude] delegate:nil cancelButtonTitle:@"OK" otherButtonTitles: nil];
[alert show];
}
@end