IOS中電池變化的監聽

1,電池級別和電池狀態監聽通知
[[UIDevice currentDevice] setBatteryMonitoringEnabled:YES];
	[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(checkBattery:) name:UIDeviceBatteryStateDidChangeNotification object:nil];
	[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(checkBattery:) name:UIDeviceBatteryLevelDidChangeNotification object:nil];

2,電池的四種狀態：
NSArray *stateArray = [NSArray arrayWithObjects: @"Battery state is Unknown", @"Battery is not plugged into a charging source", @"Battery is charging", @"Battery state is full", nil];

 3，[[UIDevice currentDevice] batteryLevel] * 100];//電池的級別，通常都是0.0--1.0之間；

[[UIDevice currentDevice] batteryState]；//電池的狀態

完整代碼：

- (void) doLog: (NSString *) formatstring, ...
{
	va_list arglist;
	if (!formatstring) return;
	va_start(arglist, formatstring);
	NSString *outstring = [[[NSString alloc] initWithFormat:formatstring arguments:arglist] autorelease];
	va_end(arglist);
	[self.log appendString:outstring];
	[self.log appendString:@"\n"];
	self.textView.text = self.log;
}

- (void) checkBattery: (id) sender
{
	NSArray *stateArray = [NSArray arrayWithObjects: @"Battery state is Unknown", @"Battery is not plugged into a charging source", @"Battery is charging", @"Battery state is full", nil];
	self.log = [NSMutableString string];
	[self doLog:@"Battery level: %0.2f%", [[UIDevice currentDevice] batteryLevel] * 100];
	[self doLog:@"Battery state: %@", [stateArray objectAtIndex:[[UIDevice currentDevice] batteryState]]];
}

- (void) viewDidLoad
{
	self.navigationController.navigationBar.tintColor = COOKBOOK_PURPLE_COLOR;

	// Enable battery monitoring
	[[UIDevice currentDevice] setBatteryMonitoringEnabled:YES];
	[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(checkBattery:) name:UIDeviceBatteryStateDidChangeNotification object:nil];
	[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(checkBattery:) name:UIDeviceBatteryLevelDidChangeNotification object:nil];

	// Keep checking
	[NSTimer scheduledTimerWithTimeInterval:0.1f target:self selector:@selector(checkBattery:) userInfo:nil repeats:YES];
}