ios - Firebase 检索数据并将其传递给变量

Question

ridvankucuk Problem

func getHandleStatus() -> String {
    var handle = String()
    ref.queryOrderedByChild("status").observeEventType(.ChildAdded, withBlock: { snapshot in
        if let status = snapshot.value["status"] as? Int {
            if status == 0 {
                //print(snapshot.key)
                handle = snapshot.key
            } else {
                print("NO")
            }
        }
    })
    return handle
}

当我返回“handle”时，它始终为空字符串。我设置了变量“handle = snapshot.key”，当我返回时，它仍然是空的。请帮忙。

Answer 1

首先，您的方法是异步的，并且它不等待主线程。所以写 return 是没有意义的。你应该做点别的事。在函数外部定义一个变量，例如:

var handle: String? = nil {
        didSet{
            // You know handle is set now
        }
    }

并更新您的 getHandleStatus 方法:

func getHandleStatus(){
    var handle = String()
    ref.queryOrderedByChild("status").observeEventType(.ChildAdded, withBlock: { snapshot in
        if let status = snapshot.value["status"] as? Int {
            if status == 0 {
                //print(snapshot.key)
                self.handle = snapshot.key
            } else {
                print("NO")
            }
        }
    })
}