Swift 核心数据:如何获取数组中的所有项目?
Swift Core Data: How to fetch all items in array?
我想删除我的 NSManagedObjects Weather 和 Currently 的现有内容。
let entityNames = ["Weather", "Currently"]
for entityName in entityNames {
let fetchRequest = NSFetchRequest(entityName: entityName)
let objects = try(context.execute(fetchRequest)) as? [NSManagedObject]
for object in objects! {
context.deletedObjects(object)
}
}
但是使用此代码时,我在第 3 行收到一条错误消息:
Generic parameter 'ResultType' could not be inferred
您必须指定提取请求的通用类型
let fetchRequest = NSFetchRequest<NSManagedObject>(entityName: entityName)
那你甚至可以省略结果类型
let objects = try? context.execute(fetchRequest)
还有一个错字。你可能是说
context.deleteObject(object)
在 macOS 10.11+/ iOS 9.0+ 中,我们鼓励您使用 NSBatchDeleteRequest
我想删除我的 NSManagedObjects Weather 和 Currently 的现有内容。
let entityNames = ["Weather", "Currently"]
for entityName in entityNames {
let fetchRequest = NSFetchRequest(entityName: entityName)
let objects = try(context.execute(fetchRequest)) as? [NSManagedObject]
for object in objects! {
context.deletedObjects(object)
}
}
但是使用此代码时,我在第 3 行收到一条错误消息:
Generic parameter 'ResultType' could not be inferred
您必须指定提取请求的通用类型
let fetchRequest = NSFetchRequest<NSManagedObject>(entityName: entityName)
那你甚至可以省略结果类型
let objects = try? context.execute(fetchRequest)
还有一个错字。你可能是说
context.deleteObject(object)
在 macOS 10.11+/ iOS 9.0+ 中,我们鼓励您使用 NSBatchDeleteRequest