ios - FM数据库队列死锁

Question

我正在使用 FMDatabaseQueue 并将其设置为单例

static FMDatabaseQueue* sharedDatabase;

+ (FMDatabaseQueue *)sharedDatabase
{
  if (sharedDatabase == nil) sharedDatabase = [FMDatabaseQueue databaseQueueWithPath:DATABASE_PATH];

  return sharedDatabase;
}

当我这样调用inDatabase方法时，会导致死锁...

[[UserData sharedDatabase] inDatabase:^(FMDatabase *db) {
  FMResultSet * rs = [db executeQuery:@"SELECT id FROM table1"];
  if([rs next]) {
    [[NSNotificationCenter defaultCenter] postNotificationName:kNotification1 object:aObject userInfo:@{@"key":@1}]; 
  }else{
    [[NSNotificationCenter defaultCenter] postNotificationName:kNotification1 object:aObject userInfo:@{@"key":@0}]; 
  }
  [rs close];
}];

---

另一个 Controller 观察通知

- (void)update:(NSNotification *)notification
{
  NSNumber *key = [notification.userInfo objectForKey:@"key"];
  if ([key isEqual:@1]){
    [[UserData sharedDatabase] inDatabase:^(FMDatabase *db) {
      [db executeUpdate:@"UPDATE table1 SET number = ?",1];
    }];
  }
}

谁有解决这个问题的想法...？

Answer 1

执行查询后发送通知怎么样？

__block BOOL result;

[[UserData sharedDatabase] inDatabase:^(FMDatabase *db) {
  FMResultSet * rs = [db executeQuery:@"SELECT id FROM table1"];
  result = ([rs next]) ? YES : NO;
  [rs close];
}];

[[NSNotificationCenter defaultCenter] postNotificationName:kNotification1 object:aObject userInfo:@{@"key":@result}];