Question

使用来自iOS 8 / Swift 1的教程创建一个示例应用程序，尝试使用Xcode 7.3 / Swift 2.2将文本分配给标签。提前谢谢。

import UIKit

class ViewController: UIViewController {

    @IBOutlet var ageCat: UITextField!

    @IBOutlet var resultAge: UILabel!

    @IBAction func findAgeButton(sender: AnyObject) {

        var enteredAge = Int(ageCat.text!)

        var catYears = enteredAge! * 7

        resultAge = "Your cat is \(catYears) in cat years"

    }
}

Answer 1

用以下内容替换您的IBAction func findAgeButton：

@IBAction func findAgeButton(sender: AnyObject) {

// Here the variable is unwrapped. This means the code after it is not executed unless the program is sure that it contains a value.
if let text =  ageCat.text {
    // You can use the unwrapped variable now and won't have to place an exclamation mark behind it to force unwrap it. 
    let enteredAge = Int(text)
     if let age  = enteredAge {
      let catYears = age * 7
      resultAge.text = "Your cat is \(catYears) in cat years"
   }
  }
}

Answer 2

感谢所有有用的输入。这对我有用：

@IBAction func findAgeButton(sender: AnyObject) {

     var catYears = Int(ageCat.text!)!

     catYears = catYears * 7

     resultAge.text = "Your cat is \(catYears) in cat years"

  }

我还添加了一个if / else来处理nil条目：

if Int(ageCat.text!) != nil {

    // --insert last 3 lines of code from above here--

  } else {

    resultAge.text = "Please enter a number"

}

Answer 3

您需要为resultAge.text而不是resultAge：

指定值

resultAge.text = "Your cat is \(catYears) in cat years"

将代码中的文本分配给UILabel！ Swift 2.2

3 个答案: