在下面的函数中，一切正常，除非我尝试将变量partnerName从A点获取到B点，即将变量移入闭包之外。我是一名新手编码员，所以我希望有人可以帮助我发现如何解决这个特定问题，并指出我可以学习如何在函数的不同部分之间共享变量的基础知识的地方。
func getAllConversations(handler: @escaping (_ conversationsArray: [Conversation]) -> ()) {
var partner = [""]
var title: String = ""
var partnerName = ""
var conversationsArray = [Conversation]()
REF_CONVERSATION.observeSingleEvent(of: .value) { (conversationSnapshot) in
guard let conversationSnapshot = conversationSnapshot.children.allObjects as? [DataSnapshot] else { return}
for conversation in conversationSnapshot {
let memberArray = conversation.childSnapshot(forPath: "members").value as! [String]
partner = memberArray.filter {$0 != (Auth.auth().currentUser?.uid)!}
if memberArray.contains((Auth.auth().currentUser?.uid)!) {
let newPartner = (String(describing: partner))
title = newPartner.replacingOccurrences(of: "[\\[\\]\\^+<>\"]", with: "", options: .regularExpression, range: nil)
databaseRef.child("bodhi").child(title).observeSingleEvent(of: .value, with: { (snapshot) in
if let bodhiDict = snapshot.value as? [String: AnyObject]
{
//I realize that the variable is being wrongly redeclared here to make this run.
let partnerName = (bodhiDict["Name"] as! String)
print ("partnerName returned from firebase: \(partnerName)")
// Point A: This prints "Sandy"
}
})
print ("partnerName: \(partnerName)")
// Point B: This prints nothing but if I add partnerName = "Sandy", then the function complete
title = partnerName
print ("new title: \(title)")
let conversation = Conversation(conversationTitle: title, key: conversation.key, conversationMembers: memberArray, conversationMemberCount: memberArray.count)
conversationsArray.append(conversation)
}
}
handler(conversationsArray)
}
}
func createGroup(withTitle title: String, andDescription description: String, forUserIds ids: [String], handler: @escaping (_ groupCreated: Bool) -> ()) {
REF_GROUPS.childByAutoId().updateChildValues(["title": title, "description": description, "members": ids])
// need to add code here for slow internet: if successful connection true else error
handler(true)
}
func getAllGroups(handler: @escaping (_ groupsArray: [Group]) -> ()) {
var groupsArray = [Group]()
REF_GROUPS.observeSingleEvent(of: .value) { (groupSnapshot) in
guard let groupSnapshot = groupSnapshot.children.allObjects as? [DataSnapshot] else { return}
for group in groupSnapshot {
let memberArray = group.childSnapshot(forPath: "members").value as! [String]
if memberArray.contains((Auth.auth().currentUser?.uid)!) {
let title = group.childSnapshot(forPath: "title").value as! String
let description = group.childSnapshot(forPath: "description").value as! String
let group = Group(title: title, description: description, key: group.key, members: memberArray, memberCount: memberArray.count)
groupsArray.append(group)
}
}
handler(groupsArray)
}
}
}
最佳答案
我建议您阅读有关闭包的文档:
关闭
闭包:捕获值
关于swift - 从 swift/firebase 闭包内部修改变量，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/50221660/