Arrays for Swift2

Question

I have two seperate .swift files. And I want to use ManagePerson.swift to manage my Strings such as adding and retrieving. The other ViewController.swift creates an array of ManagePerson class for accessing the data.

In my ManagePerson.swift

func addPerson(name: String, code: String, description: String){
    self.name = name
    self.code = code
    self.description = description
}

In my ViewController.swift.

var personList = [PersonTable]() // Declared at class level

for jsonObjectString in resultArray! {
    let name = jsonObjectString["Name"] as! String
    let code = jsonObjectString["Code"] as! String
    let description = jsonObjectString["Description"] as! String
    self.personList[count].addPerson(Name, code: code, description: description)
    count++
}

However, I can't seem to perform .addPerson method. I get an error of "Thread: 6: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)"

Answer 1

First, let's imagine you defined your "person" class with (a) three properties; and (b) an init method to set these properties:

class Person {
    let name: String
    let code: String
    let description: String

    init(name: String, code: String, description: String) {
        self.name = name
        self.code = code
        self.description = description
    }
}

Then, to instantiate a Person , it's just

let person = Person(name: "Joe Montana", code: "16", description: "Quarterback")

If you want an array of these Person objects, you define it as:

var personList = [Person]()

And thus, to add a Person to this array, it is:

personList.append(Person(name: "Joe Montana", code: "16", description: "Quarterback"))

So, if resultArray is an array of dictionaries, you add items like so:

for dictionary in resultArray! {
    let name = dictionary["Name"] as! String
    let code = dictionary["Code"] as! String
    let description = dictionary["Description"] as! String
    personList.append(Person(name: name, code: code, description: description))
}

But, note, we don't have to mess with count (as you can just add to the array).

Or, if these values could be nil , you'd define these as optionals:

class Person {
    let name: String?
    let code: String?
    let description: String?

    init(name: String?, code: String?, description: String?) {
        self.name = name
        self.code = code
        self.description = description
    }
}

and

for dictionary in resultArray! {
    let name = dictionary["Name"] as? String
    let code = dictionary["Code"] as? String
    let description = dictionary["Description"] as? String
    personList.append(Person(name: name, code: code, description: description))
}

Answer 2

这是因为self.personList[count]为nil它不包含任何PersonTable实例