檢查很多空的參數？

Question

我的代碼檢查一個空的參數：

if let isEmpty = name?.isEmpty where isEmpty == false { 

，但我需要實現的代碼來檢查，如果很多都是假的？例如數量和價格以及名稱......我將如何使用此代碼得到這方面的信息？

if let isEmpty = name?.isEmpty where isEmpty == false { 
    if let isEmpty = total?.isEmpty where isEmpty == false { 
     if let isEmpty = price?.isEmpty where isEmpty == false { 
      if let isEmpty = quantity?.isEmpty where isEmpty == false { 
      } 
     } 
    } 
} 

當我把它們的列表，它不起作用，當我在循環的末尾做一個try catch循環。

@IBAction func saveItems(sender: AnyObject) { 
    let name = txtName.text 
    let total = txtTotal.text 
    let price = txtPrice.text 
    let quantity = stepperValue.text 

    if let isEmpty = name?.isEmpty || 
      isEmpty = price?.isEmpty || 
      isEmpty = total?.isEmpty || 
      isEmpty = quantity?.isEmpty where isEmpty == false { 

    } 

    // Create Entity 
    let entity = NSEntityDescription.entityForName("Item", inManagedObjectContext: self.managedObjectContext) 

    // Initialize Record 
    let record = NSManagedObject(entity: entity!, insertIntoManagedObjectContext: self.managedObjectContext) 

    // Populate Record 
    record.setValue(txtName, forKey: "name") 
    record.setValue(txtTotal, forKey: "total") 
    record.setValue(txtPrice, forKey: "price") 
    record.setValue(stepperValue, forKey: "quantity") 
    record.setValue(NSDate(), forKey: "date") 

    do { 
     // Save Record 
     try record.managedObjectContext?.save() 

     // Dismiss View Controller 
     dismissViewControllerAnimated(true, completion: nil) 

    } 
    catch { 
     let saveError = error as NSError 
     print("\(saveError), \(saveError.userInfo)") 

     // Show Alert View 
     showAlertWithTitle(title: "Warning", message: "Your message could not be saved", cancelButtonTitle: "OK") 
    } 

} 
else { 
    // Show Alert View 
    showAlertWithTitle("Warning", message: "Your to-do needs a name.", cancelButtonTitle: "OK") 
} 

Answer 1

一種解決方案是一個很大的（但單一，沒有嵌套），複雜if聲明：

if let name = name, total = total, price = price, quantity = quantity 
    where !name.isEmpty && !total.isEmpty && !price.isEmpty && !quantity.isEmpty { 

    // use name, total, price, quantity 

} 

---

另外，可以說是更好的解決方案是解開他們一次一個，步進並且每個變量都有一個guard語句。

guard let name = name, total = total, price = price, quantity = quantity 
    where !name.isEmpty && !total.isEmpty && !price.isEmpty && !quantity.isEmpty else { 

    // something was nil or empty 
    return 

} 

// use name, total, price, quantity 

---

：

guard let name = name where !name.isEmpty else { 
    // name is nil or empty 
    return 
} 

guard let total = total where !total.isEmpty else { 
    // total is nil or empty 
    return 
} 

guard let price = price where !price.isEmpty else { 
    // price is nil or empty 
    return 
} 

guard let quantity = quantity where !quantity.isEmpty else { 
    // quantity is nil or empty 
    return 
} 

// use name, total, price, and quantity, all are non-nil, non-empty 

---

當然，這取決於你在裏面是零或空與不中的情況下做什麼，第一個解決方案可能是更好的一個guard書面

如果我正在編寫此代碼，假設爲nil或爲空表示數據無法保存到數據庫的狀態，那麼我會選擇兩個guard之一謝謝，我選擇哪一個取決於如何描述我想要的消息給用戶。

Answer 2

您可以創建自己的isEmpty函數，它接受一個可選的字符串，如果字符串爲零或空，則返回true。然後，要一次檢查多個，您可以創建一組您想要檢查的字符串，並將其過濾爲清空。

let arr = [name, total, price, quantity] 

let isEmpty = { (string: String?) -> Bool in 
    guard let string = string where !string.isEmpty else { return true } 
    return false 
} 

// if none of the strings are empty 
if arr.filter(isEmpty).isEmpty { 
    // do stuff 
} 

你也可以讓自己的any功能上Array或SequenceType的擴展，它可能比過濾好。

Answer 3

required_params = array('name','price',..)//all the keys required. 
input_params = array('name'=>'abc', 'price'=>20,...)//input array in which conditions are to be checked. 
foreach(required_params as $key_required){ 
    if(input_params[$key_required] is empty?) 
    return false; 
// if you dont have input_params array and have variables. just check 
//${$key_required} is empty 
    ..... 
}