我在将数据保存在核心数据中时遇到问题。我必须通过单击按钮将多个书籍信息保存在数据库中。当我单击按钮时，我调用该方法并将书籍信息保存在数据库中。前三下点击可以很好地保存图书信息，并且 ui 也是响应式的。当我第四次单击该按钮时，用户界面会在保存结束时冻结。
代码如下。
+(void) storeBookInfo:(NSDictionary *) bookInfo inContext:(NSManagedObjectContext *) ctx {
AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
NSManagedObjectContext *tempCtx = [[NSManagedObjectContext alloc]initWithConcurrencyType:NSPrivateQueueConcurrencyType];
[tempCtx setPersistentStoreCoordinator:appDelegate.persistentStoreCoordinator];
[tempCtx setUndoManager:nil];
NSNotificationCenter *notify = [NSNotificationCenter defaultCenter];
[notify addObserver:self
selector:@selector(mergeChanges:)
name:NSManagedObjectContextDidSaveNotification
object:tempCtx];
NSFetchRequest *req = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Book" inManagedObjectContext:tempCtx];
[req setEntity:entity];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"bid==%@", [bookInfo objectForKey:@"bid"]];
[req setPredicate:predicate];
[req setFetchLimit:1];
[req setReturnsObjectsAsFaults:NO];
NSArray *bookObjects = [tempCtx executeFetchRequest:req error:nil];
if([bookObjects count] > 0){
NSError *err;
Book *wi = [bookObjects objectAtIndex:0];
wi.purchaseInfo = [NSNumber numberWithInt:[[bookInfo objectForKey:@"purchaseInfo"] intValue]];
if (![tempCtx save:&err]) {
NSLog(@"Problem saving book info..");
NSLog(@"err: %@", [err userInfo]);
[[NSNotificationCenter defaultCenter] removeObserver:self];
[tempCtx undo];
tempCtx = nil;
} else {
NSLog(@"Book saved. in if part");
tempCtx = nil;
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
}
else {
Book *book = [NSEntityDescription insertNewObjectForEntityForName:@"Book" inManagedObjectContext:tempCtx];
book.bid = [bookInfo objectForKey:@"bid"];
book.title = [bookInfo objectForKey:@"title"];
book.thumbnailImgId = [bookInfo objectForKey:@"imageUrl"];
book.downloadState = [NSNumber numberWithInt:0];
book.pid = [bookInfo objectForKey:@"pid"];
book.purchaseInfo = [NSNumber numberWithInt:[[bookInfo objectForKey:@"purchaseInfo"] intValue]];
book.discription = [bookInfo objectForKey:@"desc"];
NSError *err;
if (![tempCtx save:&err]) {
NSLog(@"Problem saving book ifo..");
NSLog(@"err: %@", [err userInfo]);
[[NSNotificationCenter defaultCenter] removeObserver:self];
[tempCtx undo];
tempCtx = nil;
} else {
NSLog(@"Book saved.");
tempCtx = nil;
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
}
}
+ (void)mergeChanges:(NSNotification*)notification
{
AppDelegate *theDelegate = [[UIApplication sharedApplication] delegate];
[[theDelegate managedObjectContext] performSelectorOnMainThread:@selector(mergeChangesFromContextDidSaveNotification:) withObject:notification waitUntilDone:YES];
}
我创建了一个临时 MOC，因为代码在后台线程中，每次保存后我都会发送通知。
对于按钮应用程序的第四次点击获得冻结。我被困在这一点上。