How to reference UILabel strong reference programmatically using Swift?

Question

Using Swift, I have a UILabel that was created programmatically in the viewDidLoad override function:

var middleDate = UILabel(frame: CGRect(x: (screenWidth / 2) - 45, y: 0, width: 90, height: 20))
    middleDate.text = "3:13:46 PM"
    middleDate.font = UIFont(name: "ArialMT", size: 13)
    middleDate.textAlignment = .Center

Which works great.

Then I am trying to change the text in the override function viewDidAppear. I get Build Failed with the message Use of unresolved identifier 'middleDate'

If I use interface builder and drag and drop a UILabel on the view, then give it a strong reference it works great. Is there a way to reference a programmatically created object with a strong reference?

Or am I going about this incorrect?

This is what I have on my ViewController.swift:

I have a feeling that there is a much better and cleaner way to do this.

override func viewDidLoad() {

    super.viewDidLoad()

    var middleDate = UILabel(frame: CGRect(x: (screenWidth / 2) - 45, y: 0, width: 90, height: 20))
    middleDate.text = "3:13:46 PM"
    middleDate.font = UIFont(name: "ArialMT", size: 13)
    middleDate.textAlignment = .Center

    self.myTopView.addSubview(middleDate)
}

override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(animated)

    var timer = NSTimer.scheduledTimerWithTimeInterval(1.0,
        target: self,
        selector: Selector("getLocalTime:"),
        userInfo: nil,
        repeats: true)

    let mainLoop = NSRunLoop.mainRunLoop()
    mainLoop.addTimer(timer, forMode: NSDefaultRunLoopMode)

    func getLocalTime(timer: NSTimer) { 

        var todaysDate:NSDate = NSDate()
        var dateFormatter:NSDateFormatter = NSDateFormatter()
        var centerDateFormatter:NSDateFormatter = NSDateFormatter()

        dateFormatter.dateFormat = "h:mm:ss"            

        var DateInFormat:String = dateFormatter.stringFromDate(todaysDate)            

        middleDate.text = "hello"


    }
}

Have a class memner: "var middleDate: UILabel?". Use same in viewDidLoad and viewDidAppear. — gagarwal
– gagarwal, Commented Oct 22, 2014 at 22:21
I am adding 'var middleDate: UILabel?' to the viewDidLoad and the viewDidAppear and I am getting errors. errors: UILabel does not have a member named 'text'. And where is created the UILabel and added to the sub view I am also getting errors — Eric
– Eric, Commented Oct 22, 2014 at 23:22
The code you provided does not display a UILabel on the view. It makes a local variable containing a UILabel which is reinitialized as soon as viewDidLoad exits. If you are adding the label to your view at some later point, how are you getting a reference to the label in your viewWillAppear? You don't show that code. In short, we need to see more code. — Daniel T.
– Daniel T., Commented Oct 22, 2014 at 23:51

Steve Rosenberg · Accepted Answer · 2014-10-23 03:33:18Z

3

Try this:

class ViewController: UIViewController {

    var middleDate = UILabel(frame: CGRect(x: (360 / 2) - 45, y: 200, width: 90, height: 20))

    override func viewDidLoad() {

        super.viewDidLoad()

        middleDate.text = "3:13:46 PM"
        middleDate.font = UIFont(name: "ArialMT", size: 13)
        middleDate.textAlignment = .Center

        self.view.addSubview(middleDate)
    }

    override func viewDidAppear(animated: Bool) { super.viewDidAppear(animated)

        middleDate.text = "hello"
    }
}

Your issue was middleDate was declared with local scope within the viewDidLoad function. In order for it to be a class variable you need to declare it at the class level. I simplified the class a little just to make it work quickly for me.

answered Oct 23, 2014 at 3:33

Steve Rosenberg

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1 Comment

aremvee Over a year ago

for a few unique Labels that's the way to go, but if i was creating an array of UILabels to be iterated over as part of an update, then that's beyond my knowledge

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