Thread 1: EXC_BAD_ACCESS (code=1, address=0x176b)

Question

When I try to make a simple app, I get this error:

@IBAction func pickButton(sender: UIButton) {
    numberLabel.text = String(format: "The number is %@", randomNumber) Thread 1: EXC_BAD_ACCESS (code=1, address=0x176b)
}

Here is the full code:

import UIKit

class ViewController2: UIViewController {
    @IBOutlet weak var numberLabel: UILabel!
    @IBOutlet weak var pickButton: UIButton!
    var randomNumber = arc4random_uniform(10000) + 1
    override func viewDidLoad() {
        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.
    }

    @IBAction func pickButton(sender: UIButton) {
        numberLabel.text = String(format: "The number is %@", randomNumber)
    }
}

Please help, I don't know what I should do.

Answer 1

The %@ format is for printing Foundation objects such as NSString, NSNumber etc.

var randomNumber = arc4random_uniform(10000) + 1

is a UInt32 and that is printed with %u for "unsigned integer":

numberLabel.text = String(format: "The number is %u", randomNumber)

Alternatively, use %@ and convert the integer to NSNumber:

numberLabel.text = String(format: "The number is %@", NSNumber(unsignedInt: randomNumber))

But in your case the easiest solution is to use string interpolation:

numberLabel.text = "The number is \(randomNumber)"

Answer 2

randomNumber in an integer, not an object. The format specifier %@ expects an object. Use an appropriate format specifier such as %u.

See String Format Specifiers for documentation.