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January 17, 2017 11:09
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StrategyExample
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| import Foundation | |
| // First define the algorithm protocol. | |
| protocol LoadBehaviour { | |
| func execute() -> String | |
| } | |
| // Define the algorithms. | |
| // Algorithm 1 | |
| class CoreDataManager: LoadBehaviour { | |
| func execute() -> String { | |
| return "CoreData should be called.." | |
| } | |
| } | |
| // Algorithm 2 | |
| class ApiManager: LoadBehaviour { | |
| func execute() -> String { | |
| return "API is safe to call, there's internet." | |
| } | |
| } | |
| // The client calling LoadBehaviour. | |
| class LoadClient: AnyObject { | |
| // Behaviour can be changed during runtime. | |
| var behaviour: LoadBehaviour | |
| // Make sure the client has a default behaviour. | |
| init(_ initialBehaviour: LoadBehaviour) { | |
| self.behaviour = initialBehaviour | |
| } | |
| func load() { | |
| print(self.behaviour.execute()) | |
| } | |
| } | |
| // Create the client with a default behaviour. | |
| // We don't know whether we have internet, so first | |
| // load data from CoreData, just to be sure. | |
| var client = LoadClient(CoreDataManager()) | |
| client.load() | |
| // Imagine we suddenly connect to WiFi. | |
| client.behaviour = ApiManager() | |
| // A few minutes later we want new data, but now we have a internet connection. | |
| client.load() |
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