如何從Swift中的文本字段獲取整數值？

Question

我想創建一個簡單的BMI計算器，使用身高和體重，我無法將我的UITextField字符串轉換爲整數進行計算。

這是我的工作代碼：

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. 
    } 
} 

人有什麼想法？我試圖尋找解決方案，但找不到特定於此問題的任何內容。

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個字符串，它不會採取詮釋。

更改此：

solutionTextField.text = weightInt/(heightInt*heightInt) 

要這樣：

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

Answer 3

我不認爲你的代碼工作。要從UITextField s中獲取這些值並將它們轉換爲Ints，您需要將它們從'.text屬性中提取出來。然後，當您計算結果時，您需要將其轉換回字符串，並將solutionTextField?.text設置爲等於該結果。

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. 
    } 
} 

請記住，這個代碼是非常危險的，因爲你不能安全地展開自選，但是這是一個不同的線程。

希望這會有所幫助。

Answer 4

爲了安全，你應該做的「可選綁定」，也檢查輸入的驗證（如果該字符串轉換爲「內部」）：

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... 
}