iOS Interview Question (Part 4)

1. Can we use let property with protocol?

No, it is not possible to use a let property with a protocol in Swift.

Properties declared in a protocol are by default read-write, and you cannot specify a let property in a protocol.

4. Diff b/w Tight Coupling vs Loose Coupling

Tight Coupling means one class is dependent on another class.
Loose Coupling means one class is dependent on interface rather than class.

5. Diff b/w dependency inversion principle vs dependency injection in ios

• Dependency Inversion Principle (DIP) focuses on the design principle that encourages using abstractions (interfaces or protocols) to depend on, rather than concrete implementations. It helps in achieving loose coupling and modular design.
• Dependency Injection (DI) is a pattern that implements DIP by providing dependencies to a class from the outside. In iOS, this can be achieved through constructor injection, property injection, or method injection. DI helps in managing and providing dependencies to classes, making them more flexible and testable.

In summary, DIP is a design principle that promotes depending on abstractions, while DI is a pattern that implements DIP by externalizing the dependency management and providing dependencies to classes from the outside. By applying DIP and DI principles, you can create more modular, flexible, and testable iOS applications.

6. What is the difference between while and repeat-while loops in swift?

In Swift, the while and repeat-while loops are used for repetitive execution of code blocks, but they differ in when they evaluate their condition. Here's how they differ:

1. while Loop: The while loop evaluates its condition before executing the code block. If the condition evaluates to true, the code block is executed. If the condition is initially false, the code block is skipped entirely.

while condition {
    // Code block
}

Example:

var count = 0
while count < 5 {
    print(count)
    count += 1
}

Output:

0
1
2
3
4

In the example, the code block inside the while loop is executed as long as the condition count < 5 is true. The condition is checked before each iteration.

1. repeat-while Loop: The repeat-while loop evaluates its condition after executing the code block. This guarantees that the code block is executed at least once, regardless of the condition's initial value. If the condition evaluates to true, the loop continues to execute. If the condition is false, the loop terminates.

repeat {
    // Code block
} while condition

Example:

var count = 0
repeat {
    print(count)
    count += 1
} while count < 5

Output:

0
1
2
3
4

In the example, the code block inside the repeat-while loop is executed at least once, and then the condition count < 5 is checked. If the condition is true, the loop continues executing. If the condition is false, the loop terminates.

In summary, the key difference between while and repeat-while loops is when the condition is evaluated. The while loop evaluates the condition before executing the code block, while the repeat-while loop evaluates the condition after executing the code block.

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