BisonCreative & development notes

Tools & releasesHistorical technical note

Detecting device locking in an iOS app

Records SpringBoard lock-notification handling used to investigate a failure in an embedded game when the device locked. It preserves the troubleshooting approach and callback code; the conditions under which those interfaces may be used need separate verification.

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Originally credited to Bison. Content is retained as published.

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"Health is the foundation of everything. Getting more exercise is the way to go." Bison

A recent project contains an embedded game, and the app crashes as soon as the screen locks. I spent a long time looking for a solution.

The code is as follows

Core code

#define NotificationLock CFSTR("com.apple.springboard.lockcomplete")

#define NotificationChange CFSTR("com.apple.springboard.lockstate")

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    
    [self lookLockScreen];

    return YES;
    
}

- (void)lookLockScreen
{
    CFNotificationCenterAddObserver(CFNotificationCenterGetDarwinNotifyCenter(), NULL, screenLockStateChanged, NotificationLock, NULL, CFNotificationSuspensionBehaviorDeliverImmediately);

    CFNotificationCenterAddObserver(CFNotificationCenterGetDarwinNotifyCenter(), NULL, screenLockStateChanged, NotificationChange, NULL, CFNotificationSuspensionBehaviorDeliverImmediately);


}

static void screenLockStateChanged(CFNotificationCenterRef center,void* observer,CFStringRef name,const void* object,CFDictionaryRef userInfo)

{

    NSString* lockstate = (__bridge NSString*)name;

    if ([lockstate isEqualToString:(__bridge  NSString*)NotificationLock]) {

        //锁屏
        NSLog(@"locked.");

    } else {
        //锁屏状态改变
        NSLog(@"lock state changed.");

    }

}