如何从Swift中的文本字段获取整数值？

Question

我想创建一个简单的BMI计算器，使用身高和体重，我无法将我的UITextField字符串转换为整数进行计算。

这是我的工作代码：

import UIKit 

class BMICalculator: UIViewController { 
    //MARK: Properties 
    @IBOutlet weak var weightField: UITextField! 
    @IBOutlet weak var heightField: UITextField! 
    @IBOutlet weak var solutionTextField: UILabel! 

    @IBAction func calcButton(_ sender: AnyObject) { 
     let weightInt = Int(weightField) 
     let heightInt = Int(heightField) 

     solutionTextField.text = weightInt/(heightInt*heightInt) 
    } 

    override func viewDidLoad() { 
     super.viewDidLoad() 
    } 

    override func didReceiveMemoryWarning() { 
     super.didReceiveMemoryWarning() 
     // Dispose of any resources that can be recreated. 
    } 
} 

人有什么想法？我试图寻找解决方案，但找不到特定于此问题的任何内容。

Answer 1

使用此：

guard let text1 = weightField.text else { 
    return 
} 

guard let text2 = heightField.text else { 
    return 
} 

guard let weightInt = Int(text1) else { 
    return 
} 

guard let heightInt = Int(text2) else { 
    return 
} 

solutionTextField.text = weightInt /(heightInt*heightInt) 
//Change your name for this outlet 'solutionTextField' to 'solutionLabel' since it is a UILabel not UITextField 

Answer 2

的文本字段只接受一个字符串，它不会采取诠释。

更改此：

solutionTextField.text = weightInt/(heightInt*heightInt) 

要这样：

solutionTextField.text = String(weightInt/(heightInt*heightInt)) 

Answer 3

我不认为你的代码工作。要从UITextField s中获取这些值并将它们转换为Ints，您需要将它们从'.text属性中提取出来。然后，当您计算结果时，您需要将其转换回字符串，并将solutionTextField?.text设置为等于该结果。

class BMICalculator: UIViewController { 
    //MARK: Properties 
    @IBOutlet weak var weightField: UITextField! 
    @IBOutlet weak var heightField: UITextField! 
    @IBOutlet weak var solutionTextField: UILabel! 

    @IBAction func calcButton(_ sender: AnyObject) { 
    let weightInt = Int((weightField?.text!)!) 
    let heightInt = Int((heightField?.text!)!) 

    let solution = weightInt!/(heightInt!*heightInt!) 

    solutionTextField?.text = "\(solution)" 
    } 

    override func viewDidLoad() { 
     super.viewDidLoad() 
    } 

    override func didReceiveMemoryWarning() { 
     super.didReceiveMemoryWarning() 
     // Dispose of any resources that can be recreated. 
    } 
} 

请记住，这个代码是非常危险的，因为你不能安全地展开自选，但是这是一个不同的线程。

希望这会有所帮助。

Answer 4

为了安全，你应该做的“可选绑定”，也检查输入的验证（如果该字符串转换为“内部”）：

if let weightInt = weightField.text where Int(weightInt) != nil, let heightInt = heightField.text where Int(heightInt) != nil { 
    // you can do "String Interpolation" to get the solution string: 
    // now it is fine to use the "Force Unwrapping", already checked 
    let solution = "\(Int(weightInt)!/(Int(heightInt)! * Int(heightInt)!))" 
    solutionTextField.text = solution 
} else { 
    // invalid input... 
}