代码复制-swift3

这里是swift3 noob，如果这是个愚蠢的问题，请原谅

我曾多次遇到这个问题，但一直无法解决。如何避免下面的代码重复

@IBAction func logOutButton(_ sender: Any) {

    var userEntered = usernameText.text!

    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let context = appDelegate.persistentContainer.viewContext

    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")

    request.predicate = NSPredicate(format: "username = %@", "xyz")

    do {

        let results = try context.fetch(request)

    } catch {

        print ("Delete failed")
    }

}

@IBAction func submitButton(_ sender: Any) {
    var users = [String]()
    var userEntered = usernameText.text!
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let context = appDelegate.persistentContainer.viewContext


    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")


    let newValue = NSEntityDescription.insertNewObject(forEntityName: "Users", into: context)

    newValue.setValue(userEntered, forKey: "username")

    request.returnsObjectsAsFaults = false

    do {
        try context.save()

@iAction func logOutButton（\uSender:Any）{
var userEntered=usernameText.text！
让appDelegate=UIApplication.shared.delegate为！appDelegate
让上下文=appDelegate.persistentContainer.viewContext
let request=NSFetchRequest（entityName:“用户”）
request.predicate=NSPredicate（格式：“用户名=%@”，“xyz”）
做{
let results=try context.fetch（请求）
}抓住{
打印（“删除失败”）
}
}
@iAction func submitButton（\发送方：任意）{
var users=[String]（）
var userEntered=usernameText.text！
让appDelegate=UIApplication.shared.delegate为！appDelegate
让上下文=appDelegate.persistentContainer.viewContext
let request=NSFetchRequest（entityName:“用户”）
让newValue=NSEntityDescription.insertNewObject（forEntityName:“用户”，插入：上下文）
setValue（用户输入，forKey:“用户名”）
request.returnsObjectsAsFaults=false
做{
尝试context.save（）

正如你所看到的，下面的代码在两个按钮中都是重复的。我如何避免这种情况呢？我曾尝试用一种方法编写它，但我一定是做错了什么，这会引发很多错误

    var userEntered = usernameText.text!
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let context = appDelegate.persistentContainer.viewContext


    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")

var userEntered=usernameText.text！
让appDelegate=UIApplication.shared.delegate为！appDelegate
让上下文=appDelegate.persistentContainer.viewContext
let request=NSFetchRequest（entityName:“用户”）

---

谢谢

只需创建一个返回函数，返回一个

NSFetchRequest

func getFetchRequest() -> NSFetchRequest {
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let context = appDelegate.persistentContainer.viewContext
    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")
    return request
}

func getFetchRequest（）->NSFetchRequest{
让appDelegate=UIApplication.shared.delegate为！appDelegate
让上下文=appDelegate.persistentContainer.viewContext
let request=NSFetchRequest（entityName:“用户”）
退货申请
}

创建一个返回NSFetchRequest的函数

func getRequest() -> NSFetchRequest {
  var userEntered = usernameText.text!
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let context = appDelegate.persistentContainer.viewContext
    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")
}

---

请说明您尝试了什么以及遇到了什么错误。为什么不将您多次使用的代码放在一个函数中，然后调用该函数？使用

NSManagedObject

子类，它避免了大量样板代码。然后您可以编写

let request=Users.fetchRequest（）

@IBAction func logOutButton(_ sender: Any) {
    let request = getRequest()
    request.predicate = NSPredicate(format: "username = %@", "xyz")
    do {
        let results = try context.fetch(request)
    } catch {
        print ("Delete failed")
    }
}