How to declare a 'protected' variable in swift

swift class swift3 encapsulation
iProgram picture iProgram · Jan 20, 2017 · Viewed 22.4k times · Source

I want to create a class that inherits from another class, which is in a diffrent file.

For example:

Class1.swift

class Class1
{
    protected var 
    //Do Stuff
}

Class2.swift

class Class2:Class1
{
    //Do stuff
}

How would I beable to have accsess to a'protected' variable/function in swift?

When I declare a private variable/function, I can only use it in that class. If I use 'fileprivate', my other class HAS to be in the save file as Class1. What I want to do is keep my classes in seporate files and use the Groups from within Xcode to know what class belongs with which category.

Answer

Keiwan picture Keiwan · Jan 20, 2017

You would have to use internal for that as Swift doesn't offer a protected keyword (unlike many other programming languages). internal is the only access modifier between fileprivate and public:

Internal access enables entities to be used within any source file from their defining module, but not in any source file outside of that module. You typically use internal access when defining an app’s or a framework’s internal structure.

There is a blog post that explains a little bit more about why the language designers chose not to offer a protected keyword (or anything equivalent).

Some of the reasons being that

It doesn’t actually offer any real protection, since a subclass can always expose “protected” API through a new public method or property.

and also the fact that protected would cause problems when it comes to extensions, as it wouldn't be clear whether extensions should also have access to protected properties or not.

Related questions

Why Choose Struct Over Class?

Playing around with Swift, coming from a Java background, why would you want to choose a Struct instead of a Class? Seems like they are the same thing, with a Struct offering less functionality. Why choose it then?

Read More
Static vs class functions/variables in Swift classes?

The following code compiles in Swift 1.2: class myClass { static func myMethod1() { } class func myMethod2() { } static var myVar1 = "" } func doSomething() { myClass.myMethod1() myClass.myMethod2() myClass.myVar1 = "abc" } What is the difference between a static function and a class function? Which one …

Read More
What is the difference between static func and class func in Swift?

I can see these definitions in the Swift library: extension Bool : BooleanLiteralConvertible { static func convertFromBooleanLiteral(value: Bool) -> Bool } protocol BooleanLiteralConvertible { typealias BooleanLiteralType class func convertFromBooleanLiteral(value: BooleanLiteralType) -> Self } What's the difference between a member function defined …

Read More