What’s a strong reference, and why do we need it?

A strong reference in Swift is a type of reference that increases the reference count of an object, ensuring that the object is not deallocated as long as at least one strong reference to it exists. This is the default type of reference in Swift, meaning that whenever you create a reference to an object without specifying otherwise, it is a strong reference.

Why Do We Need Strong References?

Strong references are essential for ensuring that objects remain in memory as long as they are needed. Here are some key points about why strong references are necessary:

1. Memory Management: Strong references are crucial for managing the lifecycle of objects. They ensure that objects are kept alive as long as they are needed, preventing premature deallocation. This is particularly important in scenarios where objects are shared across different parts of an application.

2. Automatic Reference Counting (ARC): Swift uses ARC to manage memory. ARC keeps track of the number of strong references to each object. When the reference count drops to zero, ARC automatically deallocates the object, freeing up memory. This mechanism helps in preventing memory leaks and managing memory efficiently[1][2][4].

3. Default Behavior: In Swift, references are strong by default. This simplifies the development process because developers do not need to explicitly specify the reference type in most cases. It ensures that objects are retained as long as they are needed without additional coding effort[2][4].

4. Avoiding Retain Cycles: While strong references are necessary, they can lead to retain cycles if not managed properly. A retain cycle occurs when two or more objects hold strong references to each other, preventing ARC from deallocating them. To avoid this, developers can use weak or unowned references where appropriate[2][3][5].

Example of Strong Reference

Here is a simple example to illustrate a strong reference in Swift:

class Person {
    var name: String
    var friend: Person?
    
    init(name: String) {
        self.name = name
    }
}

var john: Person? = Person(name: "J...