向后兼容解决方案:

SEL requestSelector = NSSelectorFromString(@"requestWhenInUseAuthorization");
if ([CLLocationManager authorizationStatus] == kCLAuthorizationStatusNotDetermined &&
    [self.locationManager respondsToSelector:requestSelector]) {
    [self.locationManager performSelector:requestSelector withObject:NULL];
} else {
    [self.locationManager startUpdatingLocation];
}

在Info.plist中设置NSLocationWhenInUseUsageDescription键

解决方案与向后兼容，不产生Xcode警告:

SEL requestSelector = NSSelectorFromString(@"requestWhenInUseAuthorization");
if ([CLLocationManager authorizationStatus] == kCLAuthorizationStatusNotDetermined &&
  [self.locationManager respondsToSelector:requestSelector]) {
((void (*)(id, SEL))[self.locationManager methodForSelector:requestSelector])(self.locationManager, requestSelector);
  [self.locationManager startUpdatingLocation];
} else {
  [self.locationManager startUpdatingLocation];
}

在Info.plist中设置NSLocationWhenInUseUsageDescription键。

对于iOS版本11.0+: 在Info.plist中设置NSLocationAlwaysAndWhenInUseUsageDescription键。还有另外2把钥匙。

苹果的文件显示:

https://developer.apple.com/documentation/corelocation/requesting_permission_to_use_location_services https://developer.apple.com/documentation/corelocation/cllocationmanager/1620562-requestwheninuseauthorization

As of iOS 8, the presence of a NSLocationWhenInUseUsageDescription or a NSLocationAlwaysUsageDescription key value in your app's Info.plist file is required. It's then also necessary to request permission from the user prior to registering for location updates, either by calling [self.myLocationManager requestWhenInUseAuthorization] or [self.myLocationManager requestAlwaysAuthorization] depending on your need. The string you entered into the Info.plist will then be displayed in the ensuing dialog.

如果用户授予了权限，则业务照常进行。如果他们拒绝权限，则委托不会被告知位置更新。

用于询问位置的旧代码将无法在iOS 8中使用。您可以尝试使用此方法进行位置授权:

- (void)requestAlwaysAuthorization
{
    CLAuthorizationStatus status = [CLLocationManager authorizationStatus];

    // If the status is denied or only granted for when in use, display an alert
    if (status == kCLAuthorizationStatusAuthorizedWhenInUse || status ==        kCLAuthorizationStatusDenied) {
        NSString *title;
        title = (status == kCLAuthorizationStatusDenied) ? @"Location services are off" :   @"Background location is not enabled";
        NSString *message = @"To use background location you must turn on 'Always' in the Location Services Settings";

        UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:title
                                                            message:message
                                                           delegate:self
                                                  cancelButtonTitle:@"Cancel"
                                                  otherButtonTitles:@"Settings", nil];
        [alertView show];
    }
    // The user has not enabled any location services. Request background authorization.
    else if (status == kCLAuthorizationStatusNotDetermined) {
        [self.locationManager requestAlwaysAuthorization];
    }
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    if (buttonIndex == 1) {
        // Send the user to the Settings for this app
        NSURL *settingsURL = [NSURL URLWithString:UIApplicationOpenSettingsURLString];
        [[UIApplication sharedApplication] openURL:settingsURL];
    }
}

我也因为同样的问题而抓狂。Xcode给出错误:

试图启动MapKit位置更新而没有提示 位置授权。必须调用-[CLLocationManager requestWhenInUseAuthorization]或-[CLLocationManager . request requestAlwaysAuthorization]。

但即使实现了上述方法之一，它也不会提示用户，除非信息中有条目。NSLocationAlwaysUsageDescription或NSLocationWhenInUseUsageDescription。

添加以下行到您的信息。Plist，其中字符串值代表您需要访问用户位置的原因

<key>NSLocationWhenInUseUsageDescription</key>
<string>This application requires location services to work</string>

<key>NSLocationAlwaysUsageDescription</key>
<string>This application requires location services to work</string>

我认为自从我在Xcode 5中开始这个项目以来，这些条目可能已经丢失了。我猜Xcode 6可能会为这些键添加默认条目，但还没有确认。

你可以在这里找到更多关于这两个设置的信息

为了确保这与iOS 7向后兼容，你应该检查用户运行的是iOS 8还是iOS 7。例如:

#define IS_OS_8_OR_LATER ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0)

//In ViewDidLoad
if(IS_OS_8_OR_LATER) {
   [self.locationManager requestAlwaysAuthorization];
}

[self.locationManager startUpdatingLocation];