I can't continue with my app and I can't test run it because something is wrong in my code that I don't know how to fix! Here is the code:
import Foundation
extension Array {
mutating func shuffle() {
if count < 2 { return }
for i in 0..<(count - 1) {
let j = Int(arc4random_uniform(UInt32(count - i))) + i
customSwap(a: &self[i], b: &self[j])
}
}
}
func customSwap<T>(a: inout T, b: inout T) {
let temp = a
a = b
b = temp
}
The problem is that an array is a value type, and when you modify one element you change the whole array. So your call to customSwap() is passing in two references to the whole array which leads to the overlapping accesses to self error.
Instead, you could write customSwap() to take one copy of the array and the indices you want to swap:
func customSwap<T>(_ array: inout [T], _ a: Int, _ b: Int) {
let temp = array[a]
array[a] = array[b]
array[b] = temp
}
and then call it like this:
customSwap(&self, i, j)
But you don't have to do that, because Array has a built-in swapAt(_:_) defined like this:
mutating func swapAt(_ i: Int, _ j: Int)
So you could replace your customSwap call with:
self.swapAt(i, j)
But Array has a built-in shuffle() that you can just call instead of implementing it yourself.