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iOS Generics in Swift Generic Functions, Parameters and Constraints Generic Functions

Aananya Vyas
Aananya Vyas
20,157 Points
Posted by Aananya Vyas
Aananya Vyas
20,157 Points

why is the 'item' not being assigned to arr[i] ?

in xcode it says 'variable 'arr' passed by refrence before being initialised '

generics.swift 
func duplicate<T>(item: T , numberOfTimes : Int) -> [T] {
    var arr : [T]

    for var i in 0...numberOfTimes-1 {
        arr[i] = item
        i += 1
    }

return arr
}

1 Answer

Jhoan Arango
Jhoan Arango
14,575 Points
Jhoan Arango
Jhoan Arango
14,575 Points

Hello,

There are different ways on how to achieve this. You were close by using the for in loop.

Here is one way of doing it with the for in loop.

func duplicate<T>(item: T, numberOfTimes: Int) -> [T] {
    var items = [T]()

// for in loop and range.    
    for _ in 0...numberOfTimes - 1 {
        items.append(item)
    }

    return items
}

duplicate(item: "Test", numberOfTimes: 5)

Altho this is a good implementation of it, I favor the while loop for this task and the reason is that I think it's more readable. Also, the usage of the for in loop is more favorable to iterate through a sequence such as a range of numbers, and items in an array.

func duplicate<T>(item: T, numberOfTimes: Int) -> [T] {
    var items = [T]() // Empty Array

// while loop
   while items.count != numberOfTimes {
        items.append(item)
   }

    return items 
}

duplicate(item: "Test", numberOfTimes: 5)

Good luck