# Designing with Swift: Utilizing Template Method for Optimal Code
As developers, we often strive to create the most efficient and maintainable code possible. This can be a difficult task, especially when dealing with complex applications. One of the most powerful tools we have in our toolbox is the Template Method pattern. This pattern allows us to create code that is both robust and efficient. In this article, we will discuss how to use the Template Method pattern in Swift to create optimal code.
The Template Method pattern is a design pattern that allows us to define an algorithm in a base class. This algorithm can then be overriden by subclasses, allowing them to customize the behavior of the algorithm. This is done by defining abstract methods in the base class, which are then implemented by subclasses. This allows us to create a base class that contains the overall logic of the algorithm, while allowing subclasses to customize its behavior.
Let’s take a look at how we can use the Template Method pattern in Swift. We’ll start by creating a base class that defines the algorithm. For this example, we’ll use a simple algorithm that prints out a sequence of numbers. The base class will contain two abstract methods, one for printing the numbers and one for calculating the next number in the sequence.
“`swift
class NumberSequence {
func print() {
var currentValue = self.firstValue()
print(currentValue)
while let nextValue = self.nextValue(currentValue) {
print(nextValue)
currentValue = nextValue
}
}
func firstValue() -> Int {
fatalError(“This method must be overridden”)
}
func nextValue(_ value: Int) -> Int? {
fatalError(“This method must be overridden”)
}
}
“`
In the above code, we’ve defined a base class called `NumberSequence`. This class contains a `print` method, which is responsible for printing out the numbers in the sequence. This method makes use of two abstract methods, `firstValue` and `nextValue`, which must be implemented by subclasses.
Now that we have our base class, we can create a subclass that implements the required methods. For this example, we’ll create a subclass that prints out a sequence of Fibonacci numbers.
“`swift
class FibonacciSequence: NumberSequence {
override func firstValue() -> Int {
return 0
}
override func nextValue(_ value: Int) -> Int? {
if value == 0 {
return 1
} else {
return value + self.nextValue(value – 1)
}
}
}
“`
In the above code, we’ve created a subclass called `FibonacciSequence`, which inherits from `NumberSequence`. This subclass implements the `firstValue` and `nextValue` methods, which are used by the `print` method in the base class.
Now that we have our classes set up, we can use them to print out a sequence of Fibonacci numbers.
“`swift
let sequence = FibonacciSequence()
sequence.print()
“`
The above code will print out the following sequence of numbers:
“`
0
1
1
2
3
5
8
13
21
34
55
“`
As you can see, using the Template Method pattern allows us to easily create efficient and maintainable code. We can define an algorithm in a base class, and then allow subclasses to customize its behavior. This pattern is especially useful when dealing with complex algorithms, as it allows us to break down the algorithm into smaller, more manageable pieces.
In conclusion, the Template Method pattern is a powerful tool for creating efficient and maintainable code. It allows us to define an algorithm in a base class, and then allow subclasses to customize its behavior. By using this pattern, we can create code that is both robust and efficient.