Behavioral updated

Author: VamshiIITBHU14

21) Behavioural - Interpreter Design Pattern.swift

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+import UIKit
+import Foundation
+
+protocol Interpreter{
+ func hasNext() -> Bool
+ func next() -> String
+}
+
+protocol Container{
+ func getInterpreter() -> Interpreter
+}
+
+class NameRepo : Container{
+ let names = ["India" ,"Australia", "England", "NewZealand"]
+ func getInterpreter() -> Interpreter {
+ return NameInterpreter(names)
+ }
+}
+
+private class NameInterpreter : Interpreter{
+ var index = -1
+ var names = [String]()
+ 
+ init(_ names : [String]){
+ self.names = names
+ }
+ 
+ func hasNext() -> Bool {
+ if index < names.count {
+ return true
+ }
+ return false
+ }
+ 
+ func next() -> String {
+ if self.hasNext(){
+ index = index + 1
+ return names[index]
+ } else{
+ return ""
+ }
+ }
+}
+
+func main(){
+ let nr = NameRepo()
+ let interpreter = NameInterpreter(nr.names)
+ 
+ for _ in nr.names{
+ interpreter.hasNext()
+ print(interpreter.next())
+ }
+}
+
+main()
+

22) Behavioural - Mediator Design Pattern.swift

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+import UIKit
+import Foundation
+
+protocol Command{
+ func displayStatus()
+}
+
+protocol RemoteUmpire{
+ func registerTVDisplay(tvDisplay :TVDisplay)
+ func registerTVOperator(tvOperator : TVOperator)
+ func isDecisionMade() -> Bool
+ func setDecisionStatus(status : Bool)
+}
+
+class TVOperator : Command{
+ var tvUmpire:TVUmpire
+ 
+ init(_ tvUmpire : TVUmpire){
+ self.tvUmpire = tvUmpire
+ }
+ 
+ func displayStatus() {
+ if tvUmpire.isDecisionMade(){
+ print("Decision Made and Batsman in OUT")
+ tvUmpire.setDecisionStatus(status: true)
+ } else{
+ print("Decision Pending")
+ }
+ }
+ 
+ func getReady(){
+ print("Ready to Display Decision")
+ }
+}
+
+class TVDisplay : Command{
+ var tvUmpire:TVUmpire
+ 
+ init(_ tvUmpire : TVUmpire) {
+ self.tvUmpire = tvUmpire
+ tvUmpire.setDecisionStatus(status: true)
+ }
+ func displayStatus() {
+ print("Decision made and permission granted to display the decision on TV Display")
+ tvUmpire.setDecisionStatus(status: true)
+ }
+}
+
+
+
+class TVUmpire : RemoteUmpire{
+ private var tvOperator : TVOperator?
+ private var tvDisplay : TVDisplay?
+ private var decisionMade : Bool?
+ 
+ func registerTVDisplay(tvDisplay: TVDisplay) {
+ self.tvDisplay = tvDisplay
+ }
+ 
+ func registerTVOperator(tvOperator: TVOperator) {
+ self.tvOperator = tvOperator
+ }
+ 
+ func isDecisionMade() -> Bool {
+ return decisionMade!
+ }
+ 
+ func setDecisionStatus(status: Bool) {
+ self.decisionMade = status
+ }
+}
+
+func main(){
+ let tvUmpire = TVUmpire()
+ let tvDisplayAtGround = TVDisplay(tvUmpire)
+ let tvOperatorAtGround = TVOperator(tvUmpire)
+ tvUmpire.registerTVDisplay(tvDisplay: tvDisplayAtGround)
+ tvUmpire.registerTVOperator(tvOperator: tvOperatorAtGround)
+ tvOperatorAtGround.getReady()
+ tvDisplayAtGround.displayStatus()
+ tvOperatorAtGround.displayStatus()
+ 
+ 
+}
+
+main()
+
+
+

23) Behavioural - Memento Design Pattern.swift

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+//Assume you are adding the stats (number of runs scored) of a cricketer year by year in your program and at some point of time you want to trace back to an year in the past and check his stats till that point of time
+
+import UIKit
+
+class Memento {
+ let numberOfRunsScored : Int
+ 
+ init(_ numberOfRunsScored : Int){
+ self.numberOfRunsScored = numberOfRunsScored
+ }
+}
+
+//StatsHolder is an imaginary hardware which displays the stats
+
+class StatsHolder : CustomStringConvertible{
+ 
+ private var numberOfRunsScored : Int
+ 
+ init(_ numberOfRunsScored : Int) {
+ self.numberOfRunsScored = numberOfRunsScored
+ }
+ 
+ func addStatsToHolder (_ runsToBeAdded : Int) -> Memento{
+ numberOfRunsScored += runsToBeAdded
+ return Memento(numberOfRunsScored)
+ }
+ 
+ func restoreToPastStat(_ memento : Memento){
+ numberOfRunsScored = memento.numberOfRunsScored
+ }
+ 
+ var description: String{
+ return "Total Runs scored = \(numberOfRunsScored)"
+ }
+}
+
+func main(){
+ let statsHolder = StatsHolder(1200) //1200 is the first stat (number of runs) we add to stats holder
+ let stat1 = statsHolder.addStatsToHolder(1400)
+ let stat2 = statsHolder.addStatsToHolder(700)
+ 
+ print(statsHolder)
+ 
+ //restoreToStat1
+ statsHolder.restoreToPastStat(stat1)
+ print(statsHolder)
+ 
+ //restoreToStat2
+ statsHolder.restoreToPastStat(stat2)
+ print(statsHolder)
+ 
+ //There is no memento/snapshot when the StatsHolder is initialised
+}
+
+
+main()
+

24) Behavioural - Null Object Design Pattern.swift

@@ -0,0 +1,67 @@
+import Foundation
+
+protocol Log
+{
+ func bowlerStatsFromCurrentMatch(_ stats: String)
+ func batsmenStatsFromCurrentMatch(_ stats: String)
+}
+
+class StatsDisplayLog : Log
+{
+ func bowlerStatsFromCurrentMatch(_ stats: String) {
+ print(stats)
+ }
+ 
+ func batsmenStatsFromCurrentMatch(_ stats: String) {
+ print(stats)
+ }
+}
+
+class NoDisplayStatsLog : Log
+{
+ func bowlerStatsFromCurrentMatch(_ stats: String) {}
+ func batsmenStatsFromCurrentMatch(_ stats: String) {}
+}
+
+
+class UserInterface
+{
+ var log: Log
+ var runsScored = 0
+ var wicketsTaken = 0
+ 
+ init(_ log: Log)
+ {
+ self.log = log
+ }
+ 
+ func wicketTaken (){
+ wicketsTaken += 1
+ log.bowlerStatsFromCurrentMatch("Total Wickets : \(wicketsTaken)")
+ }
+ 
+ func runsScored(numberOFRunsScored : Int){
+ runsScored += numberOFRunsScored
+ log.batsmenStatsFromCurrentMatch("Total Runs : \(runsScored)")
+ }
+ 
+}
+
+
+func main()
+{
+ let ipadLog = StatsDisplayLog()
+ let iPAdUserInterface = UserInterface(ipadLog)
+ iPAdUserInterface.runsScored(numberOFRunsScored: 4)
+ iPAdUserInterface.runsScored(numberOFRunsScored: 3)
+ iPAdUserInterface.wicketTaken()
+ 
+ let iPhoneLog = NoDisplayStatsLog()
+ let iPhoneUserInterface = UserInterface(iPhoneLog)
+ iPhoneUserInterface.runsScored(numberOFRunsScored: 6)
+ iPhoneUserInterface.runsScored(numberOFRunsScored: 2)
+ 
+}
+
+main()
+