CODEWITHSUNDEEP
swift
giwook
giwook

Reputation: 580

How to use arc4random_uniform to randomly select a value from an array

I have an array with a few values that I'd like to select a value from randomly but I'm having some trouble with the execution. I'm new to Swift so I'm not sure what I'm doing wrong here.

let types = ["value1", "value2", "value3"]

class someClass {
    let type = String(arc4random_uniform(UInt32(types)))
}

With this code, I get the error Playground execution failed: <EXPR>:39:16: error: cannot invoke 'init' with an argument of type 'UInt32' let type = String(arc4random_uniform(UInt32(types))) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I tried something a little different to see if I could workaround this error.

let types = ["value1", "value2", "value3"]

class someClass {
    let x = arc4random_uniform(UInt32(4))
    let type = types[x]
}

But then I get this error: Playground execution failed: <EXPR>:39:22: error: 'BlogPost.Type' does not have a member named 'x' let type = types[x] ^

I've only been working with Swift for a month so far so I'd definitely appreciate it if you guys could share your insight on both of the methods I tried, and if both methods are correctable how would you rework the code for both examples to make it work?

Upvotes: 2

Views: 1860

Answers (1)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726489

Here is how you can do it:

let types = ["value1", "value2", "value3"]
let type = types[Int(arc4random_uniform(UInt32(types.count)))]
println(type)
  • The cast of count to UInt32 is necessary because arc4random_uniform takes an unsigned value
  • The cast of arc4random_uniform back to Int is required because array subscript operator [] takes an Int.

Demo (click [Compile] at the bottom to run).

Upvotes: 5

Related Questions