防止ios6下中文输入时，锁屏lock screen导致crash
- (void)applicationDidEnterBackground:(UIApplication *)application{ if (kCFCoreFoundationVersionNumber > kCFCoreFoundationVersionNumber_iOS_5_1) { // Acquired additional time UIDevice *device = [UIDevice currentDevice]; BOOL backgroundSupported = NO; if ([device respondsToSelector:@selector(isMultitaskingSupported)]) { backgroundSupported = device.multitaskingSupported; } if (backgroundSupported) { __block UIBackgroundTaskIdentifier backgroundTask = [application beginBackgroundTaskWithExpirationHandler:^{ [application endBackgroundTask:backgroundTask]; backgroundTask = UIBackgroundTaskInvalid; }]; } }}