Calling values from a random row in Parse? - ios

Question

I'm trying to figure out how to call values from all columns for each variable within a random row, and each row is denoted by its own specific objectId, which is the name of the column, on Parse. Here is where I've defined the values of the variables in each column:
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
var voteCount1 = PFObject(className: "VoteCount")
voteCount1["choices"] = 2
voteCount1["votes"] = Int()
voteCount1["votes2"] = Int()
voteCount1["optionName"] = String()
voteCount1["optionName2"] = String()
}
I've figured out how to make it so that a button will send a vote to a variable's vote count (defined as an Int) in the row of a specific object ID, but I don't know how to call polls from a random Object ID and send votes to the corresponding choices in that row. Here's my IBAction of adding votes to a variable of a specific object ID:
#IBAction func addVote1(sender: AnyObject) {
for button in self.buttons {
button.enabled = false
}
var query = PFQuery(className: "VoteCount")
query.getObjectInBackgroundWithId("BiEM17uUYT") {
(voteCount1: PFObject!, error: NSError!) ->Void in
if error != nil {
NSLog("%#", error)
} else {
voteCount1.incrementKey("votes")
voteCount1.saveInBackgroundWithTarget(nil, selector: nil)
}
let votes = voteCount1["votes"] as Int
let votes2 = voteCount1["votes2"] as Int
let percent1 = votes * 100 / (votes + votes2)
let percent2 = votes2 * 100 / (votes + votes2)
self.pollResults1.text = "\(percent1)% (\(votes)) \(percent2)% (\(votes2))"
}
}
How do I call values from random rows?
UPDATE: I just tried the following re-written from objective-C but I'm not sure if it's right:
var query = PFQuery(className: "VoteCount")
query.findObjectsInBackgroundWithBlock {
(objects: NSArray, error: NSError!) -> Void in
if error == nil {
randNumber = arc4random_uniform(count)
query2.whereKey("voteNumber", equalTo:randNumber)
query2.getFirstObjectInBackgroundWithBlock {
(voteCount1: PFObject!, error: NSError!) -> Void in
if error != nil {
NSLog("%#", error)
} else {
let votes = voteCount1["votes"] as Int
let votes2 = voteCount1["votes2"] as Int
let option1 = voteCount1["optionName"] as String
let option2 = voteCount1["optionName2"] as String
self.showOption1.text = "\(option1)"
self.showOption2.text = "\(option2)"
}
}
}

Answer 1

You would never hard-code object ids in your code. In order to fetch a random row, simply fetch all of the rows from Parse and then select one at random.
For example
PFQuery *query = [PFQuery queryWithClassName:#"VoteCount"];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error) {
NSInteger index=arc4random_uniform(objects.count);
NSLog("The random object is %#",objects[index]);
} else {
// Log details of the failure
NSLog(#"Error: %# %#", error, [error userInfo]);
}
}];
For a more useful implementation you would probably store the objects array into a property so that you could refer to it from outside the block.
Note that by default, only the first 100 rows will be returned. You can increase the limit up to 1000. Beyond 1000 you have to use paging with multiple queries. See https://parse.com/questions/fetch-all-data-in-a-table-using-pfquery
var query = PFQuery(className: "VoteCount")
query.findObjectsInBackgroundWithBlock {
(objects: NSArray, error: NSError!) -> Void in
if error == nil {
if let randomObject=objects[arc4random_uniform(objects.count)] {
println("The random object is \(randomObject)\")
}
} else {
println("error \(error)")
}
}