Applying an NSTimer to a UILabel (Swift) - swift

Question

i'm quite new to using swift and i'm currently working on a small school project. However, one function i cant seem to work out is how to make an NSTimer change the text in a UILabel after a certain amount of time. I want to apply this function to a UILabel (cannotbuy) that was blank, and had just been changed to text displaying a message("you dont have enough points"), and i want this message to be removed and the UILabel to be blank again after a second or so. Can anyone help me? Thanks.
class Upgrades: UIViewController{
#IBOutlet weak var shprogresslabel: UILabel!
#IBOutlet weak var fsprogresslabel: UILabel!
#IBOutlet weak var shprogress: UIProgressView!
#IBOutlet weak var fsprogress: UIProgressView!
#IBOutlet weak var shbutton: UIButton!
#IBOutlet weak var fsbutton: UIButton!
#IBOutlet weak var storepoints: UILabel!
#IBOutlet weak var cannotbuy: UILabel!
#IBOutlet weak var label2: UILabel!
#IBOutlet weak var label1: UILabel!
var fsprice = Int()
var shprice = Int()
let defaults = NSUserDefaults.standardUserDefaults()
func updateProgress1(){
fsprogress.progress += 0.1
let fsprogressvalue = self.fsprogress.progress
fsprogresslabel.text = "\(fsprogressvalue * 100)%"
}
func updateProgress2(){
shprogress.progress += 0.2
let shprogressvalue = self.shprogress.progress
shprogresslabel.text = "\(shprogressvalue * 100)%"
}
#IBAction func button2(sender: AnyObject) {
if shprice <= 90{
if SharingManager.sharedInstance.totalscore >= shprice{
SharingManager.sharedInstance.shiphealth = SharingManager.sharedInstance.shiphealth + 1
SharingManager.sharedInstance.totalscore = SharingManager.sharedInstance.totalscore - fsprice
storepoints.text = String(SharingManager.sharedInstance.totalscore)
shprice = shprice + 20
print(shprice)
label2.text = ("\(shprice)")
defaults.setInteger(SharingManager.sharedInstance.shiphealth, forKey: "SharingManager.sharedInstance.shiphealth")
updateProgress2()
}else{
cannotbuy.text = "You dont have enough points"
}
}else{
cannotbuy.text = "You have purchased all the available upgrades for this"
}
}
#IBAction func button1(sender: AnyObject) {
if fsprice <= 100{
if SharingManager.sharedInstance.totalscore >= fsprice{
SharingManager.sharedInstance.bulletspeed = SharingManager.sharedInstance.bulletspeed - 0.15
SharingManager.sharedInstance.totalscore = SharingManager.sharedInstance.totalscore - fsprice
storepoints.text = String(SharingManager.sharedInstance.totalscore)
fsprice = fsprice + 10
print(fsprice)
label1.text = ("\(fsprice)")
defaults.setDouble(SharingManager.sharedInstance.bulletspeed, forKey: "SharingManager.sharedInstance.bulletspeed")
updateProgress1()
}else{
cannotbuy.text = "You dont have enough points"
}
}else{
cannotbuy.text = "You have purchased all the available upgrades for this"
}
}
override func viewDidLoad() {
if fsprice == 0{
fsprice = 10
}
if shprice == 0{
shprice = 10
}
if fsprice == 180{
fsbutton.enabled = false
}
if shprice == 100{
shbutton.enabled = false
}
storepoints.text = String(SharingManager.sharedInstance.totalscore)
label1.text = ("\(fsprice)")
label2.text = ("\(shprice)")
super.viewDidLoad()
// 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.
}
}

Answer 1

There are two ways for you to do this:
Using NSTimer:
#IBAction func button2(sender: AnyObject) {
...
cannotbuy.text = "You don't have enough points"
NSTimer.scheduledTimerWithTimeInterval(5, target: self, selector: #selector(ViewController.resetCannotBuy), userInfo: nil, repeats: false)
}
func resetCannotBuy() {
cannotbuy.text = ""
}
Using dispatch_after:
#IBAction func button2(sender: AnyObject) {
...
cannotbuy.text = "You don't have enough points"
let fiveSecondLater = dispatch_time(DISPATCH_TIME_NOW, 5 * Int64(NSEC_PER_SEC))
dispatch_after(fiveSecondLater, dispatch_get_main_queue()) {
self.cannotbuy.text = ""
}
}
NSEC_PER_SEC is the constant for nanosecond per second, which is equal to 1 billion.