Swift 4-如何让函数在函数外部设置变量

var globalVariable: Int = 0

func setGlobalVariable() {
    globalVariable = 10
}

setGlobalVariable()
print(globalVariable) // 输出：10

func calculateSum(a: Int, b: Int) -> Int {
    return a + b
}

let sum = calculateSum(a: 5, b: 3)
print(sum) // 输出：8

func increment(number: inout Int) {
    number += 1
}

var count = 5
increment(number: &count)
print(count) // 输出：6

class Counter {
    var count: Int = 0
    
    func increment() {
        count += 1
    }
}

let counter = Counter()
counter.increment()
print(counter.count) // 输出：1