Swift 4函数为多个返回值返回0 [英] Swift 4 function returning 0 for multiple return values

问题描述

我一直在搜索，但是找不到解决方案.有人可以让我知道我在做什么错.这是我的功能代码:在我的数据库中，我将hour = 5设为Int，将Minute = 45设为Int但是当我打印时，该函数的值打印0,0

I have been searching around but couldn't find a solution. can someone please let me know what I am doing wrong. here is my function code: in my database I have hour=5 as Int and Minute=45 as Int but when I print, the values of the function prints 0,0

var docRefF : DocumentReference!

func getTime()-> (Int, Int){
    var FHour = Int()
    var FMinute = Int()

    docRefF = Firestore.firestore().document("sampleTime/worktime")
    dataListener =  docRefF.addSnapshotListener { (docSnapshot, error) in
        guard let docSnapshot = docSnapshot, docSnapshot.exists else { return }

        let data = docSnapshot.data()
        let Hour:Int = data["Hour"]! as! Int
        let Minute: Int = data["Minute"]! as! Int

        FHour = Hour
        FMinute = Minute
    }

    return (FHour, FMinute)
}
let time = getTime()
print("\(time.0),\(time.1)" )
 //printed 0,0

推荐答案

很显然，它是异步执行的问题.将 *函数与Closure * 结合使用，而不要使用具有返回值的函数.

Clearly its issue of asynchronous execution. Use * function with Closure* Instead of function with returning value.

请参考以下代码

var docRefF : DocumentReference!
func getTime(_ then:(_ first:Int, _ second:Int)->()){
    var FHour = Int()
    var FMinute = Int()


    docRefF = Firestore.firestore().document("sampleTime/worktime")
    dataListener =  docRefF.addSnapshotListener { (docSnapshot, error) in
     guard let docSnapshot = docSnapshot, docSnapshot.exists else { return }
   let data = docSnapshot.data()
    let Hour:Int = data["Hour"]! as! Int
    let Minute: Int = data["Minute"]! as! Int

        FHour = Hour
        FMinute = Minute

    //TODO:- Use other firebase related task same as your code, so that uncomment other lines same as your origional

    then(FHour, FMinute) // This is closure call back line

     }
   }

   //Calling your function
    getTime { (first, second) in

    print(first,second)

    }

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