在Swift 3.0之前,我们可以这样fetch数据:
@H_403_3@var people = [NSManageObject]() //1 let fetchRequest = NSFetchRequest(entityName: "Person") do { //2 let results = try managedContext.executeFetchRequest(fetchRequest) //3 people = results as! [NSManagedObject] } catch let error as NSError { print("Could not fetch \(error),\(error.userInfo)") } }不过在Swift 3.0以后,要做一些调整,首先第1句修改为:
@H_403_3@let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Person")在这里你必须明确指定一种泛型,在第2句修改如下:
@H_403_3@let results = try managedContext.fetch(fetchRequest)最后第3句不需要做改变.
其实第1句也可以这么写:
@H_403_3@let fetchRequest = NSFetchRequest<NSManagedObject>(entityName: "Person")这样第3句就可以将类型转换删掉了:
@H_403_3@people = results