Swift objects array to plist file - swift

Question

I am trying to save my object's array to array.plist but I get the following error:
Thread 1: signal SIGABRT error
My object class looks like this:
class Note {
// MARK: Properties
var title: String
var photo: UIImage?
var text: String
// MARK: Initialization
init?(title: String, photo: UIImage?, text: String) {
// Initialize stored properties.
self.title = title
self.photo = photo
self.text = text
// Initialization should fail if there is no name or if the rating is negative.
if title.isEmpty{
return nil
}
}
func encodeWithCoder(aCoder: NSCoder!) {
aCoder.encodeObject(title, forKey:"title")
aCoder.encodeObject(text, forKey:"text")
aCoder.encodeObject(photo, forKey:"photo")
}
init (coder aDecoder: NSCoder!) {
self.title = aDecoder.decodeObjectForKey("title") as! String
self.text = aDecoder.decodeObjectForKey("text") as! String
self.photo = aDecoder.decodeObjectForKey("photo") as! UIImage
}
}
In the controller, I try to save the array with the Notes object like this:
notes = [Notes]()
notes.append(note)
let paths = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory,NSSearchPathDomainMask.AllDomainsMask, true)
let path: AnyObject = paths[0]
let arrPath = path.stringByAppendingString("/array.plist")
NSKeyedArchiver.archiveRootObject(notes, toFile: arrPath)

Answer 1

Not all the properties in your class are not optional, yet when you retrieve them from the plist, you are unwrapping all of them. This might cause your code to crash.
For example, if the photo is nil and you saved the object, when you are retrieving it, you are unwrapping it self.photo = aDecoder.decodeObjectForKey("photo") as! UIImage, which will crash if you did not save anything there.
Try removing the unwrapping and check again for your crash. Even if this was not the cause of your crash, it will cause a crash at some point.
If this does not fix your problem, please paste the complete error log so it is a bit more clear what is happening.

Answer 2

For swift 5. You can save an array of custom classes to a .plist file that inherits from NSObject and NSSecureCoding.
If we create a custom class called Person:
import Foundation
class Person: NSObject, NSSecureCoding {
//Must conform to NSSecureCoding protocol
public class var supportsSecureCoding: Bool { return true } //set to 'true'
//just some generic things to describe a person
private var name:String!
private var gender:String!
private var height:Double!
//used to create a new instance of the class 'Person'
init(name:String, gender:String, height:Double) {
super.init()
self.name = name
self.gender = gender
self.height = height
}
//used for NSSecureCoding:
func encode(with coder: NSCoder) {
coder.encode(name, forKey: "name") //encodes the name to a key of 'name'
coder.encode(gender, forKey: "gender")
coder.encode(height, forKey: "height")
}
//used for NSSecureCoding:
required init?(coder: NSCoder) {
super.init()
self.name = (coder.decodeObject(forKey: "name") as! String)
self.gender = (coder.decodeObject(forKey: "gender") as! String)
self.height = (coder.decodeObject(forKey: "height") as! Double)
}
//created just to print the data from the class
public override var description: String { return String(format: "name=%#,gender=%#,height%f", name, gender, height) }
}
Now we can create functions to save and load from a .plist file in the ViewController class:
We need to gather data from the directory system of the device:
func documentsDirectory()->String {
let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
let documentsDirectory = paths.first!
return documentsDirectory
}
func dataFilePath ()->String{
return self.documentsDirectory().appendingFormat("/your_file_name_here.plist")
}
function to save the array:
func saveData(_ people:[Person]) {
let archiver = NSKeyedArchiver(requiringSecureCoding: true)
archiver.encode(people, forKey: "your_file_name_here")
let data = archiver.encodedData
try! data.write(to: URL(fileURLWithPath: dataFilePath()))
}
function to load the array:
func loadData() -> [Person] {
let path = self.dataFilePath()
let defaultManager = FileManager()
var arr = [Person]()
if defaultManager.fileExists(atPath: path) {
let url = URL(fileURLWithPath: path)
let data = try! Data(contentsOf: url)
let unarchiver = try! NSKeyedUnarchiver(forReadingFrom: data)
//Ensure the unarchiver is required to use secure coding
unarchiver.requiresSecureCoding = true
//This is where it is important to specify classes that can be decoded:
unarchiver.setClass(Person.classForCoder(), forClassName: "parentModule.Person")
let allowedClasses =[NSArray.classForCoder(),Person.classForCoder()]
//Finally decode the object as an array of your custom class
arr = unarchiver.decodeObject(of: allowedClasses, forKey: "your_file_name_here") as! [Person]
unarchiver.finishDecoding()
}
return arr
}
In the ViewController class:
override func viewDidLoad() {
super.viewDidLoad()
let testPerson = Person(name: "Bill", gender: "Male", height: 65.5)
let people:[Person] = [testPerson]
//Save the array
saveData(people)
//Load and print the first index in the array
print(loadData()[0].description)
}
Output:
[name=Bill,gender=Male,height=65.5000000]