How to Properly Declare Array of Custom Objects in

问题:

Here is my custom class...not sure if I'm missing anything in it...

import UIKit

class baseMakeUp {
    var Image = UIImage()
    var Brand: String
    var Color: String
    var Rating: Int = 0

    init (Brand: String, Color: String) {
        self.Brand = Brand
        self.Color = Color
    }
}

I'm trying to instantiate here...

import UIKit

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {

    required init(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    let cellIdentifier = "cellIdentifier"

    var foundation: [[baseMakeUp]]
    var blush: [[baseMakeUp]]
    var eyes: [[baseMakeUp]]
    var lips: [[baseMakeUp]]
    var nails: [[baseMakeUp]]

    // put some test data in makeup arrays here...
    foundation[0].Brand = "Revlon"     -------------> "Expected declaration" error.
    foundation[0].Color = "Red"
    foundation[0].Rating = 3
    foundation[1].Brand = "MAC"
    foundation[1].Color = "Blue"
    foundation[1].Rating = 4

I didn't include the rest of the ViewController class, because I didn't think it was necessary.

The error occurs when I attempt to assign a value to foundation[0].Brand

Appreciate your help in advance!

回答1:

First, I'm going to assume you didn't want 2d arrays. If you did, I'll answer your question from that perspective below.

    var foundation = [baseMakeUp]()

Creates an empty array of baseMakeUp called foundation. You can't use subscripting to add elements to an array, you can only use it to change existing elements. Since your array is empty you add elements with append.

   foundation.append(baseMakeUp(Brand: "Brand", Color: "Color"))

Since you don't have a baseMakeUp initializer that allows you to pass a rating that element's rating is 0. However since you appended it to your array you can now use subscripting to change it's Rating variable like this:

foundation[0].Rating = 3

If you did intend for 2d arrays.

    var foundation = [[baseMakeUp]]()

To create the array

    foundation.append([])
    foundation[0].append(baseMakeUp(Brand: "Brand", Color: "Color"))
    foundation[0][0].Rating = 3

The first line appends an empty array to your top level array. The second line appends a baseMakeUp to the array added in the first line. The third line uses subscripting to change the Rating of the first element in the first array of your 2d array.

Hopefully that helps with your problem.

Additionally

I was going to add points 1 and 2 from jday001s answer here, but you should check out their answer as well.

Edit

I just realized that you're trying to add elements to your arrays in the wrong scope.

You'll have to move your

foundation.append(baseMakeUp(Brand: "Brand", Color: "Color")

inside a function and call it yourself or place them inside something like viewDidLoad

eg:

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {

    var foundation = [baseMakeUp]()

    override func viewDidLoad() {
        super.viewDidLoad()

        foundation.append(baseMakeUp(Brand: "Brand", Color: "Color")
        foundation[0].Rating = 3
    }
}

Hopefully that's helpful.

回答2:

You have a few things going on here:

1. You are missing some naming conventions. Class names should be capitalized (baseMakeUp should be BaseMakeUp).
2. Class vars should be lower case (image, brand, color, rating). Also brand & color in the init method.

3. Do you intend for your foundation array to be multidimensional? If you just want a regular array, I'd go with something like:

   var foundation = [BaseMakeup]?
   

4. As the other answer says, you also need to instantiate BaseMakeup objects using your init method:

   let aBaseMakeup = BaseMakeup(brand: "Revlon", color: "Red")
   

5. After that, you can add BaseMakeup objects to your array like this:

   foundation?.append(aBaseMakeup)
   

Hopefully I'm understanding what you are trying to accomplish.

回答3:

First Create a custom class...

import Foundation

class ClassName{

  var id: Int?
  var name: String?
  var category_name: String?
  var price: Double?

   init(json: JSON) {
        self.id = json["id"].int
        self.name = json["name"].string
        self.category_name = json["category_name"].string
        self.price = json["price"].double
}

}

Use can use this Class in viewcontroller by following lines

var arrayName:Array<yourclassname> = Array()
print("/(yourclaseename[0].name)")

回答4:

You need to instantiate your class object

example:

var foundation = baseMakeUp(Brand: "Some Brand", Color: "Red")