swift - 如何访问函数内的变量然后使用它？

Question

我正在尝试访问函数 checkUser() 内的变量 i。接下来是 if 语句，if i == 0 应该 println("Displaying Picture of Others")

底部的代码不起作用，因为函数 checkUser 不返回 i 值，并且我收到错误:使用未解析的标识符 'i '，但是经过摸索并将代码调整为:

func checkUser() -> (Int?) {
    var i = 0
    return (i)
}

var (i) = checkUser()
if i == 0{
    println("Value is set")
}

并实现它，我得到一个错误int is not conversion to void。我有哪些选择可以使其发挥作用？

<小时/>

func checkUser(){
    var reqest = PFUser.query()

    reqest.whereKey("username", equalTo: self.user.username)
    reqest.whereKey("check", equalTo: true)
    reqest.findObjectsInBackgroundWithBlock {
        (objects: [AnyObject]!, error: NSError!)-> Void in
        if error == nil {
            println("Successfully retrieved \(objects.count) item.")

            var i = objects.count // variable that holds objects.count

            if let objects = objects as? [PFObject] {
                for object in objects {
                    println(object.objectId)
                    if object["check"] as Bool == true{
                        println("Displaying Picture of You")
                    }
                }
            }
        } else {
            // Log details of the failure
            println("Error: \(error) \(error.userInfo!)")
        }
    }

    if i == 0{
        println("Displaying Picture of Someone else")
    }
}

Answer 1

如果你想根据请求的结果计数显示别人的图片，你可以调用一个函数，而不是创建和检查条件:

func checkUser(){
var reqest = PFUser.query()

reqest.whereKey("username", equalTo: self.user.username)
reqest.whereKey("check", equalTo: true)
reqest.findObjectsInBackgroundWithBlock {
(objects: [AnyObject]!, error: NSError!)-> Void in
if error == nil {
  println("Successfully retrieved \(objects.count) item.")

  if (objects.count == 0) {
    displayPicture()
  }

  if let objects = objects as? [PFObject] {
    for object in objects {
      println(object.objectId)
      if object["check"] as Bool == true{
        println("Displaying Picture of You")
      }
    }
  }
} else {
  // Log details of the failure
  println("Error: \(error) \(error.userInfo!)")
}
}

displayPicture() {
   println("Displaying Picture of someone else")
  }
}