前言
很多時候我們的客戶端軟件在電腦休眠之前都需要做一些事情，比如保存，清理工作等事件簿煌。這個時候我們就希望在電腦休眠前能夠接收到通知磁携，然后有足夠的時間去處理這些事情褒侧，讓我們的軟件更好的運行，帶來更好的用戶體驗谊迄。
正文
Cocoa 和 I/O Kit都可以用來接收休眠和喚醒通知闷供，除了正常的接收通知以外，I/O Kit還可以阻止和延遲閑置休眠鳞上。注意这吻，即使是I/O Kit，也無法阻止強制休眠篙议，只能延遲強制休眠唾糯。
提示：Mac OS X 有兩種休眠模式- 強制休眠和閑置休眠.
當用戶執(zhí)行一些操作導(dǎo)致的電腦休眠是強制休眠怠硼。 盒上筆記本的蓋子，從右上角的蘋果菜單中選擇休眠都會導(dǎo)致強制休眠. 在一些特定的情況下移怯，系統(tǒng)也會觸發(fā)強制休眠, 比如, 溫度過高或電量過低.
在系統(tǒng)設(shè)置中節(jié)能下設(shè)置的時間長度下香璃，電腦都沒有被使用，則會進入閑置休眠舟误。
清單1：在Cocoa下注冊休眠和喚醒通知
- (void) receiveSleepNote: (NSNotification*) note
{
NSLog(@"receiveSleepNote: %@", [note name]);
}
- (void) receiveWakeNote: (NSNotification*) note
{
NSLog(@"receiveWakeNote: %@", [note name]);
}
- (void) fileNotifications
{
//These notifications are filed on NSWorkspace's notification center, not the default
// notification center. You will not receive sleep/wake notifications if you file
//with the default notification center.
[[[NSWorkspace sharedWorkspace] notificationCenter] addObserver: self
selector: @selector(receiveSleepNote:)
name: NSWorkspaceWillSleepNotification object: NULL];
[[[NSWorkspace sharedWorkspace] notificationCenter] addObserver: self
selector: @selector(receiveWakeNote:)
name: NSWorkspaceDidWakeNotification object: NULL];
}
提示：IOPMAssertionCreateWithName 是一個在Mac OS X 10.6雪豹系統(tǒng)下新增的API葡秒。IOPMAssertionCreateWithName 允許應(yīng)用彈出一個帶有簡要說明的提示框，告訴用戶為什么要阻止休眠嵌溢。如果你想要支持早期的Mac OS X 版本眯牧，你可能會使用到基于清單3和4的API，或者已經(jīng)被啟動的API——IOPMAssertionCreate 赖草。
清單2：在Mac OS X 10.6中使用I/O Kit阻止休眠
...
#import <IOKit/pwr_mgt/IOPMLib.h>
...
// kIOPMAssertionTypeNoDisplaySleep prevents display sleep,
// kIOPMAssertionTypeNoIdleSleep prevents idle sleep
//reasonForActivity is a descriptive string used by the system whenever it needs
// to tell the user why the system is not sleeping. For example,
// "Mail Compacting Mailboxes" would be a useful string.
// NOTE: IOPMAssertionCreateWithName limits the string to 128 characters.
CFStringRef* reasonForActivity= CFSTR("Describe Activity Type");
IOPMAssertionID assertionID;
IOReturn success = IOPMAssertionCreateWithName(kIOPMAssertionTypeNoDisplaySleep,
kIOPMAssertionLevelOn, reasonForActivity, &assertionID);
if (success == kIOReturnSuccess)
{
//Add the work you need to do without
// the system sleeping here.
success = IOPMAssertionRelease(assertionID);
//The system will be able to sleep again.
}
...
清單3：在 I/O Kit下注冊休眠和喚醒通知
#include <ctype.h>
#include <stdlib.h>
#include <stdio.h>
#include <mach/mach_port.h>
#include <mach/mach_interface.h>
#include <mach/mach_init.h>
#include <IOKit/pwr_mgt/IOPMLib.h>
#include <IOKit/IOMessage.h>
io_connect_t root_port; // a reference to the Root Power Domain IOService
void
MySleepCallBack( void * refCon, io_service_t service, natural_t messageType, void * messageArgument )
{
printf( "messageType %08lx, arg %08lx\n",
(long unsigned int)messageType,
(long unsigned int)messageArgument );
switch ( messageType )
{
case kIOMessageCanSystemSleep:
/* Idle sleep is about to kick in. This message will not be sent for forced sleep.
Applications have a chance to prevent sleep by calling IOCancelPowerChange.
Most applications should not prevent idle sleep.
Power Management waits up to 30 seconds for you to either allow or deny idle
sleep. If you don't acknowledge this power change by calling either
IOAllowPowerChange or IOCancelPowerChange, the system will wait 30
seconds then go to sleep.
*/
//Uncomment to cancel idle sleep
//IOCancelPowerChange( root_port, (long)messageArgument );
// we will allow idle sleep
IOAllowPowerChange( root_port, (long)messageArgument );
break;
case kIOMessageSystemWillSleep:
/* The system WILL go to sleep. If you do not call IOAllowPowerChange or
IOCancelPowerChange to acknowledge this message, sleep will be
delayed by 30 seconds.
NOTE: If you call IOCancelPowerChange to deny sleep it returns
kIOReturnSuccess, however the system WILL still go to sleep.
*/
IOAllowPowerChange( root_port, (long)messageArgument );
break;
case kIOMessageSystemWillPowerOn:
//System has started the wake up process...
break;
case kIOMessageSystemHasPoweredOn:
//System has finished waking up...
break;
default:
break;
}
}
int main( int argc, char **argv )
{
// notification port allocated by IORegisterForSystemPower
IONotificationPortRef notifyPortRef;
// notifier object, used to deregister later
io_object_t notifierObject;
// this parameter is passed to the callback
void* refCon;
// register to receive system sleep notifications
root_port = IORegisterForSystemPower( refCon, ¬ifyPortRef, MySleepCallBack, ¬ifierObject );
if ( root_port == 0 )
{
printf("IORegisterForSystemPower failed\n");
return 1;
}
// add the notification port to the application runloop
CFRunLoopAddSource( CFRunLoopGetCurrent(),
IONotificationPortGetRunLoopSource(notifyPortRef), kCFRunLoopCommonModes );
/* Start the run loop to receive sleep notifications. Don't call CFRunLoopRun if this code
is running on the main thread of a Cocoa or Carbon application. Cocoa and Carbon
manage the main thread's run loop for you as part of their event handling
mechanisms.
*/
CFRunLoopRun();
//Not reached, CFRunLoopRun doesn't return in this case.
return (0);
}
停止接收 I/O Kit 的休眠通知, 你需要從應(yīng)用程序的runloop中刪除事件源学少，并做一些清理工作。
清單4：移除 I/O Kit休眠/喚醒通知
...
// we no longer want sleep notifications:
// remove the sleep notification port from the application runloop
CFRunLoopRemoveSource( CFRunLoopGetCurrent(),
IONotificationPortGetRunLoopSource(notifyPortRef),
kCFRunLoopCommonModes );
// deregister for system sleep notifications
IODeregisterForSystemPower( ¬ifierObject );
// IORegisterForSystemPower implicitly opens the Root Power Domain IOService
// so we close it here
IOServiceClose( root_port );
// destroy the notification port allocated by IORegisterForSystemPower
IONotificationPortDestroy( notifyPortRef );
...
