libc++abi.dylib: terminating with uncaught exception of type NSException (lldb)

import UIKit

class ViewController: UIViewController {
var t = Timer()
@IBAction func hi(_ sender: Any) {
    print("Camera button pressed")
    t.invalidate()
}

func processTimer() {
    print("1 second has passed")
}
override func viewDidLoad() {
    super.viewDidLoad()


    t = Timer.scheduledTimer(timeInterval: 1, target: self, selector: Selector(("processTimer")), userInfo: nil, repeats: true)
    // Do any additional setup after loading the view, typically from a nib.
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}