无法将'Int'类型的值转换为预期的参数类型'UInt32'

Question

关于我可以做些什么来解决这个错误的想法，我试图得到十个随机数，这样我就可以查询firebase一组包含随机数的问题。屏幕截图如下。我还添加了代码......

import UIKit
import Firebase

class QuestionViewController: UIViewController {

var amountOfQuestions = 2

override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
}

override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(true)

    //Use a for loop to get 10 questions
    for _ in 1...10{
        //generate a random number between 1 and the amount of questions you have
        var randomNumber = Int(arc4random_uniform(amountOfQuestions - 1)) + 1

        //The reference to your questions in firebase (this is an example from firebase itself)
        let ref = Firebase(url: "https://dinosaur-facts.firebaseio.com/dinosaurs")
        //Order the questions on their value and get the one that has the random value
        ref.queryOrderedByChild("value").queryEqualToValue(randomNumber)
            .observeEventType(.ChildAdded, withBlock: {
                snapshot in
                //Do something with the question
                println(snapshot.key)
            })
    }    }



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

@IBAction func truepressed(sender: AnyObject) {
}

@IBAction func falsePressed(sender: AnyObject) {
}

Answer 1

将amountOfQuestions声明为UInt32：

var amountOfQuestions: UInt32 = 2

PS：如果你想在语法上更正，那就是数字的问题。

Answer 2

将amountOfQuestions变量设为UInt32而不是编译器推断的Int。

var amountOfQuestions: UInt32 = 2

// ...

var randomNumber = Int(arc4random_uniform(amountOfQuestions - 1)) + 1

arc4random_uniform需要UInt32。

来自Darwin docs：

arc4random_uniform(u_int32_t upper_bound);

Answer 3

第一件事： 方法＆＃34; arc4random_uniform＆＃34;期望一个类型为UInt32的参数，所以当你把那个减法放在那里时，它转换了＆＃39; 1＆＃39;你写信给UInt32。

第二件事：在swift中你不能从Int中减去UInt32（公式中的＆＃39; 1＆＃39;）（在这种情况下＆＃39; amountOfQuestions＆＃39;）。

要解决这一切，您必须考虑更改＆＃39; amountOfQuestions＆＃39;到：

var amountOfQuestions = UInt32(2)

应该这样做：）