Retrieving data from firebase depending on (City) - ios

Question

I am working on iOS application using swift, and I have the following data in firebase dashboard of the application
Users =
{
"07a5fa11-2a09-455b-92bf-a86dcd9d3e3e" =
{
Name = "Hissah";
Category = "Art & Designe";
City = "Riyadh";
Email = "H#him.fm";
ShortDescription = "";
};
"08e5443c-cdde-4fda-8733-8c4fce75dd34" =
{
Name = "Sara";
Category = "Cheefs";
City = "Dubai";
Email = "Sara#gmail.com";
ShortDescription = "best cake ever . ";
};
How can I retrieve the (Name) of the users whose (City) is "Riyadh" to a table view?
Thanks in advance.

Answer 1

Tossing this in the ring as it's a straightforward answer and addresses a dataSource that can be used to populate a tableView
let ref = Firebase(url:"https://your-app.firebaseio.com/users")
ref.queryOrderedByChild("City").queryEqualToValue("Riyadh")
.observeEventType(.Value, withBlock: { snapshot in
//iterate over all the values read in and add each name
// to an array
for child in snapshot.children {
let name = child.value["Name"] as! NSString
self.tableViewDataSourceArray.append(name)
}
//the tableView uses the tableViewDataSourceArray
// as it's dataSource
self.tableView.reloadData()
})
Edit: A follow up comment asked how to add the text to a NSTextView
ref.queryOrderedByChild("City").queryEqualToValue("Riyadh")
.observeEventType(.Value, withBlock: { snapshot in
//iterate over all the values and add them to a string
var s = String()
for child in snapshot.children {
let name = child.value["Name"] as! NSString
s += name + "\n" // the \n puts each name on a line
}
//add the string we just build to a textView
let attrString = NSAttributedString(string: s)
self.myTextView.textStorage?.appendAttributedString(attrString)
})

Answer 2

With your current node "Users" you would have to download all users and individually check to see which ones have the city "Riyadh". This would be a waste because you would be reading a lot of data you might not need.
If searching for users by city is a main feature of your app I would make another node "Cities" which would contain a list of cities. Each city node would then contain a list of all the users in that city and you could query that node. Then if you need more information on those users you know which specific people to look up in your "Users" node. You could then use this information however you see fit in your table view.
Cities:
{
"Riyadh":
{
"07a5fa11-2a09-455b-92bf-a86dcd9d3e3e":true
},
"Dubai":
{
"08e5443c-cdde-4fda-8733-8c4fce75dd34":true
}
},
Users:
{
"07a5fa11-2a09-455b-92bf-a86dcd9d3e3e":
{
Name: "Hissah";
Category: "Art & Designe";
City: "Riyadh";
Email: "H#him.fm";
ShortDescription: "";
};
"08e5443c-cdde-4fda-8733-8c4fce75dd34":
{
Name: "Sara";
Category: "Cheefs";
City: "Dubai";
Email: "Sara#gmail.com";
ShortDescription: "best cake ever . ";
};
Further reading here, where it talks about denormalizing data:
https://www.firebase.com/docs/web/guide/structuring-data.html