How do I create lazy properties and understand initialization order?

In Swift, lazy properties are properties that are not initialized until they are accessed for the first time. This provides a way to defer the initialization of properties, which can be particularly useful for properties that require complex setup or have a high setup cost. Understanding the initialization order in Swift is also crucial, especially when dealing with classes that have initializers and inherited properties.

What are Lazy Properties?

A lazy property is declared with the `lazy` keyword. The property is only initialized when it is first accessed, allowing for optimizations in memory usage and performance. Here’s how you can declare a lazy property:


    class Example {
        lazy var lazyProperty: String = {
            return "This is a lazy initialized property."
        }()
        
        var normalProperty: String = "This is a normal property."
        
        init() {
            print("Initializer called")
        }
    }
    
    let example = Example()
    print(example.normalProperty) // Output: This is a normal property.
    print(example.lazyProperty)   // Output: Initializer called, followed by: This is a lazy initialized property.

Initialization Order

In Swift, properties are initialized in the order they are defined, which is important to keep in mind when using lazy properties. Lazy properties take on the values of their enclosing instance only after the initializer of the instance is completed. Here’s a simple illustration:


    class Test {
        lazy var lazyValue: String = {
            return "Lazy Value Initialized"
        }()
        
        var earlyValue: String
        
        init() {
            earlyValue = "Early Value Initialized"
            print(earlyValue)
        }
    }
    
    let test = Test() // Output: Early Value Initialized
    print(test.lazyValue) // Output: Lazy Value Initialized

How do I create lazy properties and understand initialization order?

What are Lazy Properties?

Initialization Order

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How do I create lazy properties and understand initialization order?

What are Lazy Properties?

Initialization Order

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