TextField空检查

Question

我想添加textfield的值。我想检查textfield是否为空或检查除int之外的其他值。我是斯威夫特的新手。请帮助任何帮助将得到帮助。

@IBOutlet var label :UILabel!
@IBOutlet var first : UITextField!
@IBOutlet var third : UITextField!
@IBOutlet var second : UITextField!

var bloa :NSString?
override func viewDidLoad() {
    super.viewDidLoad()
}

@IBAction func playPressed(sender: UIButton) {

    var a: Int = 0
    var b: Int = 0
    var c: Int = 0
    var d: Int = 0


 if first.text!.isEmpty || second.text!.isEmpty || third.text!.isEmpty {
    return
 }
    else
    {

// If on first textfield there is another value than int they show 
//fatal error: unexpectedly found nil while unwrapping an Optional value 

    a = (Int)(first.text!)!
    b = Int(second.text!)!
    c = Int(third.text!)!

    d = a + b + c

   label?.text = String (format: "%d",d)
    }

Answer 1

试试这个：

if first!.text == "" || second!.text == "" || third!.text == "" {

}

Answer 2

您不需要以这种方式检查它是否为空：

let alert = UIAlertController(title: "your title", message "move to next VC?", preferredStyle: UIAlertController: UIAlertControllerStyle.Alert)
let action: UIAlertAction = UIAlertAction(title: "yes move to next VC", style: UIAlertActionStyle.Default) {action -> Void in 
    let rViewController = storyboard.instantiateViewControllerWithIdentifier("rsh") as! R_SVC
    self.presentViewController(rViewController, animated: true, completion: nil) })
alert.addAction(defaultAction)

self.presentViewController(alert, animated: true, completion: nil)

您的最终代码将是：

guard let a = Int((first?.text)!), b = Int((second?.text)!) , c = Int((third?.text)!) else {
    print("Not convertable to Int or field are empty")
    return
}

Answer 3

如果您为所有这些文本框设置键盘，如下面的屏幕截图，更改标记为红色矩形。您无需在代码中检查给定的字符/单词是否为整数。

Answer 4

从故事板中将键盘类型设置为数字键盘。然后在代码中执行此操作：

@IBAction func playPressed(sender: UIButton) {
    if first?.text?.isEmpty || second?.text?.isEmpty || third?.text?.isEmpty {

    }
}