排序coreData提取(swift4)
排序coreData提取(swift4)
提问于 2017-11-28 20:47:26
现在，我的代码正在使用NSPredicate或排序描述符来收集名称。我希望NSPredicate能从a中对所有的名字进行排序，就是这样。
孔大汉
class coreDataHandler: NSObject {
private class func getContext() -> NSManagedObjectContext{
let appDelegate = UIApplication.shared.delegate as! AppDelegate
return appDelegate.persistentContainer.viewContext
}
class func saveObject(username:String, password:String) -> Bool{
let context = getContext()
let entity = NSEntityDescription.entity(forEntityName: "User", in: context)
let managedObject = NSManagedObject(entity: entity!, insertInto: context)
managedObject.setValue(username, forKey: "username")
managedObject.setValue(password, forKey: "password")
do {
try context.save()
return true
} catch {
return false}
}
class func filterData() -> [User]? {
let conttext = getContext()
let fetchRequest:NSFetchRequest<User> = User.fetchRequest()
var user:[User]? = nil
var predicate = NSPredicate(format: "username contains[d] %@" ,"duke")
fetchRequest.predicate = predicate
do {
user = try conttext.fetch(fetchRequest)
return user
}catch {
return user
}
}真空控制
user = coreDataHandler.filterData()
for i in user! {
print("Judou : \(i.username!)")
}Stack Overflow用户
发布于 2019-10-16 03:52:39
在斯威夫特4或斯威夫特5中，你可以使用
func sortlist(){
//1
guard let appDelegate =
UIApplication.shared.delegate as? AppDelegate else {
return
}
let managedContext =
appDelegate.persistentContainer.viewContext
//2
let fetchRequest =
NSFetchRequest<NSManagedObject>(entityName: "User")
let sort = NSSortDescriptor(key: "username", ascending: false)
fetchRequest.sortDescriptors = [sort]
//3
do {
let langugeCodes = try managedContext.fetch(fetchRequest)
for result in langugeCodes as [NSManagedObject] {
var username:String = result.value(forKey: "username")! as! String
var password:String = result.value(forKey: "password")! as! String
print("username==>",username)
print("name==>",name)
}
} catch let error as NSError {
print("Could not fetch. \(error), \(error.userInfo)")
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/47540669
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