ios - 如何在按钮和警报消息上放置最大值

Question

我有一个咖啡应用程序，在累积 10 个咖啡积分后(每杯咖啡值(value) 2 积分)，您将获得一杯免费咖啡。

如何使咖啡的最大订购量为 10，并在达到 10 点时弹出警告消息。

这是排序 View 的 View Controller 。当没有订购咖啡时会出现错误消息，但我试图在用户达到 10 分时弹出另一条警报消息

import Foundation
import UIKit

class OrderingViewController: UIViewController {

    var cstudent: Student = Student("name", "000")
    var totalNumberOfCoffees = 0
    var maximumNumberOfCoffee = 10

    let minimumB = 0
    let maximumA = 10

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

    @IBAction func cappaPressed(_ sender: Any) {
        totalNumberOfCoffees += 2 
    }

    @IBAction func flatwhitePressed(_ sender: Any) {
        totalNumberOfCoffees += 2
    }

    @IBAction func mochaPressed(_ sender: Any) {
        totalNumberOfCoffees += 2
    }

    @IBAction func esspresso(_ sender: Any) {
        totalNumberOfCoffees += 2
     }


    @IBAction func placeOrderPressed(_ sender: Any) { 
    // by using this function, it makes the user know that they must order at least one 
    // coffee. if this were not here, it could waste the user's time as they 
    // may not be aware or may have made a mistake by not clicking on a coffee button.

        if totalNumberOfCoffees > 0 { // you cannot order 0 coffees
            performSegue(withIdentifier: "placeOrderSegue", sender: self)
        }
        displayAlertMessage(userMessage: "You cannot order no coffees!")

        if minimumB >= maximumA {
            totalNumberOfCoffees = maximumNumberOfCoffee
        }
        displayAlertMessage(userMessage: "FREE COFFEE")
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

        if (segue.identifier == "placeOrderSegue"){
            let datasend = segue.destination as! AccountViewController
            datasend.currentstudent = cstudent 
            // this passes the name of the student logged in, back to the 
            // AccountViewController. This is useful as if it were not here, the 
            // name of the user would be lost.

            datasend.currentstudent.numOfCoffees += totalNumberOfCoffees 
            // add coffees bought to current student. this makes the 
            // student logged in know how many coffees they're oreder.
       }
    }

    // alert message. 
    func displayAlertMessage (userMessage: String) {
        let myAlert = UIAlertController(title: "Nothing has been ordered",  message:userMessage, preferredStyle: UIAlertControllerStyle.alert)

        let okAction = UIAlertAction(title: "ok", style: UIAlertActionStyle.default, handler: nil) 
        //the okAction is the button which is pressed by the users which lets them re-order on 
        // the same view controller (orderingViewController)

        myAlert.addAction(okAction)

        self.present(myAlert, animated: true, completion: nil)
    }

}

Answer 1

1. 当达到 10 分时弹出警告消息。

简单的答案是创建一个 checkReach 函数来检查 totalNumberOfCoffees 是否大于或等于 10

@IBAction func cappaPressed(_ sender: Any) {
    totalNumberOfCoffees += 2 
    checkReach()
}

@IBAction func flatwhitePressed(_ sender: Any) {
    totalNumberOfCoffees += 2
    checkReach()
}

@IBAction func mochaPressed(_ sender: Any) {
    totalNumberOfCoffees += 2
    checkReach()
}

@IBAction func esspresso(_ sender: Any) {
    totalNumberOfCoffees += 2
    checkReach()
 }

func checkReach() {
    if totalNumberOfCoffees >= 10 {
        displayAlertMessage (userMessage: "REACHED")
        totalNumberOfCoffees = 10
    }
}