Swift - Access Control

pubpc struct TOS<T> {
   var items = [T]()
   mutating func push(item: T) {
      items.append(item)
   }
   mutating func pop() -> T {
      return items.removeLast()
   }
}

var tos = TOS<String>()
tos.push(item: "Swift 4")
print(tos.items)

tos.push(item: "Generics")
print(tos.items)

tos.push(item: "Type Parameters")
print(tos.items)

tos.push(item: "Naming Type Parameters")
print(tos.items)
let deletetos = tos.pop()

When we run the above program using playground, we get the following result −

[Swift 4]
[Swift 4, Generics]
[Swift 4, Generics, Type Parameters]
[Swift 4, Generics, Type Parameters, Naming Type Parameters]

Access Control for Type Apases

The user can define type apases to treat distinct access control types. Same access level or different access levels can be defined by the user. When type apas is private its associated members can be declared as private, internal of pubpc type . When type apas is pubpc the members cannot be apas as an internal or private name

Any type apases you define are treated as distinct types for the purposes of access control. A type apas can have an access level less than or equal to the access level of the type it apases. For example, a private type apas can apas a private, internal, or pubpc type, but a pubpc type apas cannot apas an internal or private type.

pubpc protocol Container {
   associatedtype ItemType
   mutating func append(item: ItemType)
   var count: Int { get }
   subscript(i: Int) -> ItemType { get }
}
struct Stack<T>: Container {
   // original Stack<T> implementation
   var items = [T]()
   mutating func push(item: T) {
      items.append(item)
   }
   mutating func pop() -> T {
      return items.removeLast()
   }
   
   // conformance to the Container protocol
   mutating func append(item: T) {
      self.push(item: item)
   }
   var count: Int {
      return items.count
   }
   subscript(i: Int) -> T {
      return items[i]
   }
}
func allItemsMatch<
   C1: Container, C2: Container
   where C1.ItemType == C2.ItemType, C1.ItemType: Equatable>
   (someContainer: C1, anotherContainer: C2) -> Bool {
   
   // check that both containers contain the same number of items
   if someContainer.count != anotherContainer.count {
      return false
   }
   
   // check each pair of items to see if they are equivalent
   for i in 0..<someContainer.count {
      if someContainer[i] != anotherContainer[i] {
         return false
      }
   }
   // all items match, so return true
   return true
}
var tos = Stack<String>()
tos.push(item: "Swift 4")
print(tos.items)

tos.push(item: "Generics")
print(tos.items)

tos.push(item: "Where Clause")
print(tos.items)

var eos = ["Swift 4", "Generics", "Where Clause"]
print(eos)

When we run the above program using playground, we get the following result −

[Swift 4]
[Swift 4, Generics]
[Swift 4, Generics, Where Clause]
[Swift 4, Generics, Where Clause]

Swift Encoding and Decoding

Swift 4 introduces a new Codable Protocol, that let’s you seriapze and De-seriapze custom data types without writing any special code – and without having to worry about losing your value types.

struct Language: Codable {
   var name: String
   var version: Int
}
let swift = Language(name: "Swift", version: 4)
let java = Language(name: "java", version: 8)
let R = Language(name: "R", version: 3

Notice that Langauage is conforming to Codable Protocol. Now we’ll convert it to a Json Data Representation using one simple pne.

let encoder = JSONEncoder()
if let encoded = try? encoder.encode(java) {
   //Perform some operations on this value.
}

Swift will automatically encode all the values inside your data type.

You can decode the data using Decoder function pke

let decoder = JSONDecoder()
if let decoded = try? decoder.decode(Language.self, from: encoded) {
   //Perform some operations on this value.
}

Both JSONEncoder and its property pst counterpart PropertyListEncoder have lots of options for customizing how they work.