如何知道 iOS 设备何时插入？

Question

有没有办法知道我的设备 (iPhone) 何时插入电源，例如带有 USB 端口的计算机或汽车音响系统？我在应用中使用本地化服务，并且希望在插入设备时自动更改为 kCLLocationAccuracyBestForNavigation。谢谢...

Answer 1

您可以通过 UIDevice 类 启用电池监控并检查查看电池状态以查看是否正在充电：

typedef enum {
    UIDeviceBatteryStateUnknown,
    UIDeviceBatteryStateUnplugged,
    UIDeviceBatteryStateCharging,
    UIDeviceBatteryStateFull,
} UIDeviceBatteryState;

在启用最佳 GPS 精度之前，您需要检查是否正在充电或已充满。

Answer 2

您可以注册以便在配件连接或断开连接时收到通知。

示例：

[[EAAccessoryManager sharedAccessoryManager] registerForLocalNotifications];
NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
[notificationCenter addObserver:self
                       selector:@selector(accessoryDidConnect:)
                           name:EAAccessoryDidConnectNotification
                         object:nil];
[notificationCenter addObserver:self
                       selector:@selector(accessoryDidDisconnect:)
                           name:EAAccessoryDidDisconnectNotification
                         object:nil];

一旦收到此通知，您可以使用 for 循环来遍历每个附件，例如：

NSArray *accessories = [[EAAccessoryManager sharedAccessoryManager] connectedAccessories]; 
EAAccessory *accessory = nil; 

for (EAAccessory *obj in accessories)
{ 
    // See if you're interested in this particular accessory
}

在某些时候（也许是释放）您将希望取消注册这些通知。你可以这样做：

NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
[notificationCenter removeObserver:self 
                              name:EAAccessoryDidDisconnectNotification 
                            object:nil];
[notificationCenter removeObserver:self 
                              name:EAAccessoryDidConnectNotification 
                            object:nil];
[[EAAccessoryManager sharedAccessoryManager] unregisterForLocalNotifications];  

Answer 3

检查电池状态：

UIDeviceBatteryState batteryState = [[UIDevice currentDevice] batteryState];

订阅有关电池状态变化的通知，例如通过调用您自己的操作方法 batteryStateChanged：

- (void) setup {
  [[UIDevice currentDevice] setBatteryMonitoringEnabled:YES];
  NSNotificationCenter * center= [NSNotificationCenter defaultCenter];
  [center addObserver:self
             selector:@selector(batteryStateChanged)
                 name:UIDeviceBatteryStateDidChangeNotification
               object:nil];
}

请记住在对象被释放时取消订阅：

- (void) dealloc
{
   [[NSNotificationCenter defaultCenter] removeObserver:self];
   [[UIDevice currentDevice] setBatteryMonitoringEnabled:NO];
}