斯威夫特&火力基地 |检查用户是否存在用户名 [英] Swift & Firebase | Checking if a user exists with a username
本文介绍了斯威夫特&火力基地 |检查用户是否存在用户名的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我试图允许用户通过搜索用户名来开始游戏并关注其他用户.我需要能够确保存在具有该用户名的用户.我正在使用以下代码，但尽管 if 被称为 else 并没有在它应该调用的时候被调用.
I am trying to allow users to start games with and follow other users by searching their username. I need to be able to make sure that a user with that username exists. I was using the following code but although the if is called the else does not get called when it should.
let checkWaitingRef = Firebase(url:"https://test.firebaseio.com/users")
checkWaitingRef.queryOrderedByChild("username").queryEqualToValue("(username!)")
.observeEventType(.ChildAdded, withBlock: { snapshot in
if snapshot.value.valueForKey("username")! as! String == username! {
} else {
}
JSON 数据树
{
"097ca4a4-563f-4867ghj0-6209288bd7f02" : {
"email" : "test1@tes1.com",
"uid" : "097ca4a4-563f-4867ghj0-6209288bd7f02",
"username" : "test1",
"waiting" : "0"
},
"55a8f979-ad0d-438u989u69-aa4a-45adb16175e7" : {
"email" : "test2@test2.com",
"uid" : "55a8f979-ad0d-438u989u69-aa4a-45adb16175e7",
"username" : "test2",
"waiting" : "0"
}
}
推荐答案
简单修复:
不要使用 .childAdded，因为当查询没有找到任何东西时，块将不会执行.
Don't use .childAdded as the block will not execute when the query doesn't find anything.
改为使用 .Value 并检查 NSNull
Instead use .Value and check for NSNull
let checkWaitingRef = Firebase(url:"https://test.firebaseio.com/users")
checkWaitingRef.queryOrderedByChild("username").queryEqualToValue("(username!)")
.observeEventType(.Value, withBlock: { snapshot in
if ( snapshot.value is NSNull ) {
print("not found)")
} else {
print(snapshot.value)
}
})
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