Apple Swift - 将变量放在arc4random_uniform中

问题描述

有一个相当基本的Swift问题给你。

我的目标：为了能够使用一个变量

问题：我不知道如何在createBalloons（）函数之外移动balloonCount。

解决方案？在currentIndex之上定义balloonCount，程序将识别此变量。 （我被告知这是解决方案，我只是不幸的是不知道如何做这个....）

这是我的（更新的）swift代码： / p>

  // 
 // 
 
 import UIKit 
 
 ViewController：UIViewController {
 @IBOutlet weak var balloonsLabel：UILabel！ 
 @IBOutlet weak var backgroundImageView：UIImageView！ 
 
 
 var balloons：[Balloon] = [] 
 
 var currentIndex = Int（arc4random_uniform（UInt32（balloons.count）））
  

'ViewController.type'没有名为'balloons'的成员

  override func viewDidLoad（）{
 super.viewDidLoad（）
 //加载视图之后进行任何其他设置，通常来自nib。 
 self.createBalloons（）
} 
 
 override func didReceiveMemoryWarning（）{
 super.didReceiveMemoryWarning（）
 //处理任何可以重新创建。 
} 
 
 @IBAction func nextBalloonBarButtonItemPressed（sender：UIBarButtonItem）{
 let balloon = balloons [currentIndex] 
  

'ViewController'没有名为'currentIndex'的成员

  .text =\（balloon.number）Balloon
 backgroundImageView.image = balloon.image 
 
 currentIndex = currentIndex + 1 
  pre> 
 
 
'ViewController'没有名为'currentIndex'的成员
  if currentIndex> 99 {
  
'ViewController'没有名为'currentIndex'的成员
 currentIndex = 50 
} 
 } 
 
 
 func createBalloons（）{
为var balloonCount = 0; balloonCount  
 var balloon = Balloon（）
 
 
 //我不认为你需要一个开关。 
 let randomNumber = Int（arc4random_uniform（UInt32（4）））
 
 let balloonName：String =redBalloon \（randomNumber）.jpg
 
。 image = UIImage（named：balloonName）
 balloon.number = balloonCount 
 
 self.balloons.append（balloon）
 
} 
} 
 
} 
  
 
 
解决方案
您可以为使用另一个实例变量的变量分配一个函数。
 
 
 
我会使currentIndex为Int，然后创建一个单独的getRandomIndex函数。所以代码看起来像这样：
  var currentIndex：Int！ 
 func getRandomIndex（） - > int {
 return Int（arc4random_uniform（UInt32（balloons.count）））
} 
 
 @IBAction func nextBalloonBarButtonItemPressed（sender：UIBarButtonItem）{
 currentIndex = getRandomIndex ）
 let balloon = balloons [currentIndex] 
 ... 
  
 
Got a rather basic Swift question for you all.
My goal: To be able to use a variable (count of items in an array) inside of arc4random.
Problem: I don't know how to move "balloonCount" outside of the createBalloons() function.
Solution? Define "balloonCount" above currentIndex, that way the program will recognize this variable. (I was told this is the solution, I just unfortunately do not know how to do this.... yet)
Here is my (updated) swift code:
//
//

import UIKit

class ViewController: UIViewController {
@IBOutlet weak var balloonsLabel: UILabel!
@IBOutlet weak var backgroundImageView: UIImageView!


var balloons:[Balloon] = []

var currentIndex = Int(arc4random_uniform(UInt32(balloons.count)))
'ViewController.type' does not have a member named 'balloons'
override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    self.createBalloons()
}

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

@IBAction func nextBalloonBarButtonItemPressed(sender: UIBarButtonItem) {
    let balloon = balloons[currentIndex]
'ViewController' does not have a member named 'currentIndex'
    balloonsLabel.text = "\(balloon.number) Balloon"
    backgroundImageView.image = balloon.image

    currentIndex = currentIndex + 1
'ViewController' does not have a member named 'currentIndex'
    if currentIndex > 99 {
'ViewController' does not have a member named 'currentIndex'            currentIndex = 50        }
}


func createBalloons () {
    for var balloonCount = 0; balloonCount <= 99; ++balloonCount{

        var balloon = Balloon()


        //I dont think you need a switch here.
        let randomNumber = Int(arc4random_uniform(UInt32(4)))

        let balloonName:String = "redBalloon\(randomNumber).jpg"

        balloon.image = UIImage(named: balloonName)
        balloon.number = balloonCount 

        self.balloons.append(balloon)

    }
}

}
 解决方案 
I don't think you can assign a function to a variable that uses another instance variable.
I would make currentIndex an Int and then create a seperate getRandomIndex function.  So the code would look something like this:
var currentIndex: Int!
func getRandomIndex() -> Int {
    return Int(arc4random_uniform(UInt32(balloons.count)))
}

@IBAction func nextBalloonBarButtonItemPressed(sender: UIBarButtonItem) {
    currentIndex = getRandomIndex()
    let balloon = balloons[currentIndex]
...
                        
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