What design principle ensures the safe and universal use of generic types (Generics)?

The principle of development that ensures safe and universal use of generic types (Generics) is called type safety and type parameterization.

Generics allow writing code that works with different data types, with the compiler checking type correctness at compile time, preventing runtime errors.

In Swift, this is achieved with type parameters and protocol constraints:

generic func swapValues<T>(_ a: inout T, _ b: inout T) {
    let temp = a
    a = b
    b = temp
}

Here, T is a universal type that will be substituted at call time, and the compiler guarantees that both parameters are of the same type, ensuring safety and universality.