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iOS Object-Oriented Swift 2.0 Classes Classes with Custom Types

Posted by Liam Tulit
Liam Tulit
2,973 Points

I do not get the task?

I don't get the location stuff.

classes.swift 
struct Location {
    let latitude: Double
    let longitude: Double
}

2 Answers

Steve Hunter
Steve Hunter
57,712 Points

Hi Liam,

There's a few parts to this challenge.

First you need to create a new class called Business - that has two stored properties; a name (of type String) and a location (of type Location). The Location struct is provided for us. |Both stored properties are constant, so they're declared with let not var.So, let's write the class:

class Business{
  let name:String
  let location: Location
}

The class needs an init method. This takes two parameters, the Location object and the String. These go into the init method:

init(name: String, location: Location){
  // todo
}

Inside init we set the properties of the class to the parameters passed in, so the name variable inside the class (self) is assigned the value held by the parameter that was just passed in: 

init(name: String, location: Location){
  self.name = name
  self.location = location
}

Put the init method inside the class and that's the class complete. We now need to create an instance of it called someBusiness. That's a constant too, so declared with let. We then assign a Business object to that, and pass the parameters in, as defined in the init method. That needs a name and a Location. A Location object needs creating, though. That holds two stored properties, a longitude and a latitude - both are of type Double so they can handle decimal points; not like an integer. We can create that like this:

Location(latitude: 53.2, longitude: 3.1)

That's one parameter sorted. The other is pretty simple, as it is a string. The whole init method header could look like:

Business(name: "A Business", location: Location(latitude: 53.1, longitude: 3.1))

That needs assigning to someBusiness:

let someBusiness = Business(name: "A Business", location: Location(latitude: 53.1, longitude: 3.1))

Put that lot together, and you're done!

Let me know how you get on.

Steve.

Liam Tulit
Liam Tulit
2,973 Points 
struct Location {
    let latitude: Double
    let longitude: Double
}

class Business {
    let name: String
    let location: Location

    init(name: String, location: Location){
        self.name = name
        self.location = location
        Location(latitude: 53.2, longitude: 3.1)
            }
let someBusiness = Business(name: "A Business", location: Location(latitude: 53.1, longitude: 3.1)
}

This is my code however treehouse says there are compiler errors but Xcode runs it fine??

Steve Hunter
Steve Hunter
57,712 Points
Steve Hunter
Steve Hunter
57,712 Points

Hi Liam,

You need to create the instance of the class outside its definition. Also, you've declared a Location object inside the constructor(init) that's doing nothing - you can delete that. And there's a bracket missing at the end of your instance-creation. That does throw an error in Xcode.

So, you need to clean up your init method (remove the redundant Location object), then move your someBusiness declaration outside of the class and add a bracket to it.

That should do it.

Steve.

Liam Tulit
Liam Tulit
2,973 Points

ok thanks a lot Steve!!!! :)

Steve Hunter
Steve Hunter
57,712 Points

No problem - let me know how you get on. :+1:

Steve Hunter
Steve Hunter
57,712 Points

The error output from your code isn't very illuminating, it has to be said! 

swift_lint.swift:17:99: error: expected ',' separator
let someBusiness = Business(name: "A Business", location: Location(latitude: 53.1, longitude: 3.1)
                                                                                                  ^
                                                                                                  ,
swift_lint.swift:18:1: error: expected expression in list of expressions
}
^
swift_lint.swift:17:99: error: expected ',' separator
let someBusiness = Business(name: "A Business", location: Location(latitude: 53.1, longitude: 3.1)
                                                                                                  ^
                                                                                                  ,
swift_lint.swift:18:1: error: expected ')' in expression list
}
^
swift_lint.swift:17:28: note: to match this opening '('
let someBusiness = Business(name: "A Business", location: Location(latitude: 53.1, longitude: 3.1)
                           ^
swift_lint.swift:15:9: warning: result of initializer is unused
        Location(latitude: 53.2, longitude: 3.1)

Only two are of any use - the one that says you've not closed the bracket and the one that says your Location object is unused.