swift - 在Swift 2.1中阻止存储的var

所以，我在做一个异步查询，它返回多个worker对象，每个worker都与workerperiod有一个关系，我用这个关系来做一个查询，问题是，这个查询是异步的，当它从web服务返回时，workerIndex就混乱了。

 workerQuery.whereKey("construction", equalTo: currentConstruction).findObjectsInBackgroundWithBlock({ (unsafeWorkers, error) -> Void in
            guard let workers = unsafeWorkers as? [Worker] where error == nil && workers.count == 0 else {
                return
            }

            for var workerIndex = 0; workerIndex < workers.count; workerIndex++ {

                let currentWorker = workers[workerIndex]


                if let periodQuery = WorkerPeriod.query() {
                    periodQuery.whereKey("worker", equalTo: currentWorker)

                    let weakWorkerIndex = workerIndex
                    print("weakWorkerIndex = \(weakWorkerIndex) worker \(workerIndex)")
                    periodQuery.findObjectsInBackgroundWithBlock({ (unsafeWorkerPeriod, error) -> Void in

                        guard let workerPeriods = unsafeWorkerPeriod as? [WorkerPeriod] where error == nil && workerPeriods.count != 0 else {
                            return
                        }
                        print("block weakWorkerIndex = \(weakWorkerIndex) workerIndex \(workerIndex)")

                        .
                        .

                    })
                }
            }

我试图创建一个“weakworkerindex”作为一个let来保存值，就像我们在objective-c中对块变量所做的那样，但是这不起作用，块交互只是忽略了输出中的值：

weakWorkerIndex = 0 worker 0
weakWorkerIndex = 1 worker 1
block weakWorkerIndex = 0 workerIndex 2
block weakWorkerIndex = 0 workerIndex 2
block weakWorkerIndex = 0 workerIndex 2

顺便说一下：我删除了任何不必要的代码来简化阅读过程。

最佳答案

在完成处理程序中，您需要确保workerIndex将按值捕获，例如：

for var workerIndex = 0; workerIndex < 10; workerIndex++ {
    fooAsync { [workerIndex] in
        print("\(workerIndex)")
    }
}

见swiftCapture Lists

关于swift - 在Swift 2.1中阻止存储的var，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/35159835/