Optimize Data Sending/Querying to Parse Swift iOS
I have some feedback concerning the usage of Swift optionals  in 
your code. 

The main point is that there is far too much "forced unwrapping". The forced unwrap operator ! can and should be avoided
in most cases. Instead of comparing with nil and forced unwrapping

if (parseObject != nil) {
     parseObject!.doSomething()
     parseObject!.doSomethingElse()
}


use optional binding to test and get the unwrapped value:

if let theParseObject = parseObject {
     theParseObject.doSomething()
     theParseObject.doSomethingElse()
}


Or, if parseObject is expected to be non-nil when the method
is called (e.g. because it is set up in viewDidLoad), declare it
as an implicitly unwrapped optional 

var parseObject : PFObject!
// ...
parseObject.doSomething()
parseObject.doSomethingElse()


There is no reason to declare var notes as an optional Int?.
With 

if var votes = parseObject.objectForKey("votes") as? Int { ... }


you get rid of more forced unwrap operators.

Finally, the votesLabel textfield outlet is expected to be non-nil
(otherwise you did not connect it correctly in the interface builder).
That is the reason why it is declared as an implicitly unwrapped optional
UILabel!. There is no need for optional chaining in

 votesLabel?.text = "+\(votes!)"


Putting it all together, the method should look like this:

@IBAction func happyBtn(sender: AnyObject) {

    if let theParseObject = self.parseObject {
        if var votes = theParseObject.objectForKey("votes") as? Int {
            votes++
            theParseObject.setObject(votes, forKey: "votes")
            theParseObject.saveInBackground()
            votesLabel.text = "+\(votes)"
        }
    }
}


No ! anymore!