我正在尝试添加提醒,并将用户日历添加到我的应用中。但是我遇到了一个问题,当我尝试加载保存在核心数据中的数据时,我得到的是零。加载几次后,我只获得nil数据,但每次重新加载应用程序时都会增加。
addReminderToCalendar函数
/*
*
*This function adds the reminder to the devices calendar and to the devices local storage
*
*/
func addReminderToCalendar(newReminder : Reminder){
print("adding reminder :" + newReminder.reminderName)
/*print(newReminder.reminderDescription)
print(newReminder.reminderDate)
print(newReminder.reminderID)
print(newReminder.reminderName)*/
if(newReminder.reminderID != nil && newReminder.reminderDate != nil && newReminder.reminderDescription != nil && newReminder.reminderName != nil){
//print("Adding Reminder to Calendar")
let appDelegate = UIApplication.shared.delegate as! AppDelegate!
let managedContext = appDelegate?.managedObjectContext
let entity = NSEntityDescription.entity(forEntityName: "Reminders", in:managedContext!)
let reminderDB = NSManagedObject(entity: entity!, insertInto: managedContext)
// print("Reminder ID :" + String(newReminder.reminderID))
if(checkForReminder(newReminder) == -1){//Checking that the reminder is not already added
print("addReminderToCalendar :")
print(newReminder.reminderID)
reminderDB.setValue(newReminder.reminderID, forKey: "reminderID")
reminderDB.setValue(newReminder.reminderName, forKey: "reminderName")
reminderDB.setValue(newReminder.reminderDescription, forKey: "reminderDescription")
reminderDB.setValue(newReminder.reminderDate, forKey: "reminderDate")
reminders.append(newReminder)
}
if (managedContext?.hasChanges)! {
do {
try managedContext?.save()
} catch {
//print(newReminder)
NSLog("Error Here")
}
}
}else{
print("The reminder to be added was nil")
}
}
loadReminder函数
/*
* This function loads the reminders that have been stored in the device
*/
func loadReminders(){
let appDelegate = UIApplication.shared.delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext
let fetchRequest:NSFetchRequest<NSFetchRequestResult> = NSFetchRequest(entityName: "Reminders")
let results = try? managedContext.fetch(fetchRequest)
storedReminders = results as! [NSManagedObject]
print(storedReminders.count)
//print(storedReminders[0].value(forKey: "reminderID"))
if (storedReminders.count > 0){
for index in 0 ... storedReminders.count - 1{
print("Loading reminder with ID : ")
print(storedReminders[index].value(forKey: "reminderID"))
print("Loading reminder with Name : ")
print(storedReminders[index].value(forKey: "reminderName"))
if(storedReminders[index].value(forKey: "reminderID") != nil && storedReminders[index].value(forKey: "reminderName") != nil && storedReminders[index].value(forKey: "reminderDescription") != nil && storedReminders[index].value(forKey: "reminderDate") != nil){ //checking that the values are not null
let loadedReminder = Reminder()
loadedReminder.reminderID = storedReminders[index].value(forKey: "reminderID") as! Double
loadedReminder.reminderName = storedReminders[index].value(forKey: "reminderName") as! String
loadedReminder.reminderDescription = storedReminders[index].value(forKey: "reminderDescription") as! String
loadedReminder.reminderDate = (storedReminders[index].value(forKey: "reminderDate") as! NSDate) as Date!
reminders.append(loadedReminder)
}
}
}
}
提醒课程
import Foundation
import UIKit
import CoreData
class Reminder :UICollectionViewCell{
var reminderDate: Date!
var reminderDescription: String!
var reminderID: Double!
var reminderName: String!
}
修改 我已经在我的加载提醒中添加了以下行,这是为了阻止核心数据填充nil值。 }其他{ //删除此提醒 managedContext.delete(storedReminders [index] as NSManagedObject) 打印(&#34;删除数据&#34;) } 所以我的loadReminders函数现在看起来像这个
/ * *此功能加载已存储在设备中的提醒 * / func loadReminders(){
let appDelegate = UIApplication.shared.delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext
let fetchRequest:NSFetchRequest<NSFetchRequestResult> = NSFetchRequest(entityName: "Reminders")
let results = try? managedContext.fetch(fetchRequest)
storedReminders = results as! [NSManagedObject]
print(storedReminders.count)
//print(storedReminders[0].value(forKey: "reminderID"))
if (storedReminders.count > 0){
for index in 0 ... storedReminders.count - 1{
print("Loading reminder with ID : ")
print(storedReminders[index].value(forKey: "reminderID"))
print("Loading reminder with Name : ")
print(storedReminders[index].value(forKey: "reminderName"))
if(storedReminders[index].value(forKey: "reminderID") != nil && storedReminders[index].value(forKey: "reminderName") != nil && storedReminders[index].value(forKey: "reminderDescription") != nil && storedReminders[index].value(forKey: "reminderDate") != nil){ //checking that the values are not null
let loadedReminder = Reminder()
loadedReminder.reminderID = storedReminders[index].value(forKey: "reminderID") as! Double
loadedReminder.reminderName = storedReminders[index].value(forKey: "reminderName") as! String
loadedReminder.reminderDescription = storedReminders[index].value(forKey: "reminderDescription") as! String
loadedReminder.reminderDate = (storedReminders[index].value(forKey: "reminderDate") as! NSDate) as Date!
reminders.append(loadedReminder)
}else{
//delete this reminder
managedContext.delete(storedReminders[index] as NSManagedObject)
print("deleted data")
}
}
}
}
答案 0 :(得分:1)
在这里,您要创建一个新的Reminders
实例并将其添加到NSManagedObjectContext
let entity = NSEntityDescription.entity(forEntityName: "Reminders", in:managedContext!)
let reminderDB = NSManagedObject(entity: entity!, insertInto: managedContext)
然后检查是否已添加:
if(checkForReminder(newReminder) == -1)
这是我认为问题所在。您已将Reminders
实例添加到您的上下文中!因此managedContext?.hasChanges
将是true
。
上下文发生了变化,这些Reminders
将与所有实体属性及其默认值一起保存。我假设它们默认为nil
。
这应该解决它,虽然你的代码部分我看不出来,所以把它带上了一粒盐......
func addReminderToCalendar(newReminder: Reminder) {
if(newReminder.reminderID != nil && newReminder.reminderDate != nil && newReminder.reminderDescription != nil && newReminder.reminderName != nil) {
if(checkForReminder(newReminder) == -1) {
let appDelegate = UIApplication.shared.delegate as! AppDelegate!
let managedContext = appDelegate?.managedObjectContext
let entity = NSEntityDescription.entity(forEntityName: "Reminders", in:managedContext!)
let reminderDB = NSManagedObject(entity: entity!, insertInto: managedContext)
reminderDB.setValue(newReminder.reminderID, forKey: "reminderID")
reminderDB.setValue(newReminder.reminderName, forKey: "reminderName")
reminderDB.setValue(newReminder.reminderDescription, forKey: "reminderDescription")
reminderDB.setValue(newReminder.reminderDate, forKey: "reminderDate")
reminders.append(newReminder)
if (managedContext?.hasChanges)! {
do {
try managedContext?.save()
} catch {
NSLog("Error Here")
}
}
}
} else {
print("The reminder to be added was nil")
}
}