Explore swift APIs that reduces lots of code effort

Swift - Alison Course

3. Summary of module - 1

Extensions are used to add new functionality to an existing class, structure, enumeration or protocol type. Extensions can be declared using the extension keyword.

A protocol defines a blueprint of methods, properties, and other requirements that suit a piece of functionality and can be adopted by a class, structure or enumeration. A protocol is defined similar to a class however, the protocol keyword is used.

Delegation is a simple way of connecting objects and communicate with each other and can be used to pass data between view controllers.

Mutating functions are functions that use the mutating keyword, this allows these functions to change the value of the variables in this structure or class.

Swift transformations are functions you can use on various collections and sequence types to permutate through and modify the data in an elegant way. For example the map, flatMap, compactMap, filter, reduce and zip.

4. Data structures

///Factorial with recursion
func factorial(num:Int) -> Int {
if num == 1 { return 1 }
return num * factorial(num: num - 1)
}

factorial(num: 7) //gives 5040

4. Stack implementation (LIFO)

`

//Stack implementation (LIFO)
struct Stack {
    
    private var stackArray:[String] = []  
  
   func peak() -> String? {
        return self.isEmptyStack() ? nil : stackArray.first
    }
    
    mutating func pop() -> String? {
        return self.isEmptyStack() ? nil : stackArray.removeFirst() //returns removed element
    }
    
    mutating func push(element:String) {
        stackArray.append(element)
    }
    
    func isEmptyStack() -> Bool {
        return stackArray.count == 0
    }
}

extension Stack: CustomStringConvertible {
    var description: String {
        let topLogString = "-----STACK----- \n"
        let bottomLogString = "\n------*--------\n"
        let middleLogString = stackArray.joined(separator: "\n")
        return topLogString + middleLogString + bottomLogString
    }
}

//Testing
var stackTest = Stack()
stackTest.push(element: "Eleo")
stackTest.push(element: "Combo")
stackTest.push(element: "Rambo")

print(stackTest)
/*
-----STACK----- 
Eleo
Combo
Rambo
------*--------
*/
stackTest.peak()
stackTest.pop()
/*
-----STACK----- 
Combo
Rambo
------*--------
*/
print(stackTest)


`

//BONUS: Implement generic type of stack

Using Enums :

• with combining Tuples for complex data structure.
• Polymorphism representation of collections ex. Array. That gives compile time safety check.
• Stay away from hierarchical architecture (means avoids subclass). Where we can add additional type with new property without re-arranging super class properties.