Static function variables in Swift

Question

I'm trying to figure out how to declare a static variable scoped only locally to a function in Swift.

In C, this might look something like this:

int foo() {
    static int timesCalled = 0;
    ++timesCalled;
    return timesCalled;
}

In Objective-C, it's basically the same:

- (NSInteger)foo {
    static NSInteger timesCalled = 0;
    ++timesCalled;
    return timesCalled;
}

But I can't seem to do anything like this in Swift. I've tried declaring the variable in the following ways:

static var timesCalledA = 0
var static timesCalledB = 0
var timesCalledC: static Int = 0
var timesCalledD: Int static = 0

But these all result in errors.

• The first complains "Static properties may only be declared on a type".
• The second complains "Expected declaration" (where static is) and "Expected pattern" (where timesCalledB is)
• The third complains "Consecutive statements on a line must be separated by ';'" (in the space between the colon and static) and "Expected Type" (where static is)
• The fourth complains "Consecutive statements on a line must be separated by ';'" (in the space between Int and static) and "Expected declaration" (under the equals sign)

Answer 1

I don't think Swift supports static variable without having it attached to a class/struct. Try declaring a private struct with static variable.

func foo() -> Int {
    struct Holder {
        static var timesCalled = 0
    }
    Holder.timesCalled += 1
    return Holder.timesCalled
}

  7> foo()
$R0: Int = 1
  8> foo()
$R1: Int = 2
  9> foo()
$R2: Int = 3