ios - 在 FOR 循环中创建和设置 UIButton 的标题会中断循环

Question

在我的应用程序中，我正在创建一个分页 slider (UISlider + UIPageControl)。该应用程序联系 CoreData 以获取要为其创建“页面”的实体数组。

我在以下循环中构建分页滚动条:

for i in 0..<features.count {
        var pageWidth = Int(view.frame.width)*i
        var pageView = UIView(frame: CGRectMake(CGFloat(pageWidth), 0, scrollView.frame.width, scrollView.frame.height))
        pageView.backgroundColor = UIColor.clearColor()
        pageView.clipsToBounds = true

        //Background image
        var imageView = UIImageView(frame: CGRectMake(0, 0, scrollView.frame.width, scrollView.frame.height))
        var image:UIImage!
        imageView.contentMode = .ScaleAspectFill
        pageView.addSubview(imageView)

        if fileManager.fileExistsAtPath(features[i].coverImage){
            //The background image
            image = UIImage(contentsOfFile: self.features[i].coverImage)
            imageView.image = image
        }
        else if !fileManager.fileExistsAtPath(features[i].coverImage) && !features[i].coverImage.isEmpty {
            FileStoreClient.downloadFileIfNotExists(features[i].cover, completion: { (success, error) -> Void in
                if error == nil {
                    image = UIImage(contentsOfFile: self.features[i].coverImage)
                    imageView.image = image
                }
                else {
                    println("There was an error during the download")
                }
            })
        }

        //The background cover
        var coverView = UIView(frame: CGRectMake(0, 0, view.frame.width, 250))
        coverView.backgroundColor = UIColor(red: 0, green: 0, blue: 0, alpha: 0.6)
        pageView.addSubview(coverView)

        //The title
        var titleLabel = UILabel(frame: CGRectMake(10, 40, view.frame.width-20, 25))
        titleLabel.font = UIFont(name: "Haymaker", size: 24)
        titleLabel.textColor = UIColor.whiteColor()
        titleLabel.layer.shadowColor = UIColor.blackColor().CGColor
        titleLabel.layer.shadowOffset = CGSizeMake(1, 1)
        titleLabel.layer.shadowRadius = 1
        titleLabel.layer.shadowOpacity = 1
        titleLabel.textAlignment = .Center
        titleLabel.text = features[i].title
        pageView.addSubview(titleLabel)

        //The text
        var textLabel = UILabel(frame: CGRectMake(10, titleLabel.frame.origin.y+titleLabel.frame.height+5, view.frame.width-20, 60))
        textLabel.numberOfLines = 0
        textLabel.lineBreakMode = NSLineBreakMode.ByWordWrapping
        textLabel.font = UIFont(name: "OpenSans", size: 13)
        textLabel.textColor = UIColor.whiteColor()
        textLabel.textAlignment = .Center
        textLabel.text = features[i].summary
        pageView.addSubview(textLabel)

        //The button
        var readMoreButton = UIButton(frame: CGRectMake(0, pageView.frame.height - 90, 200, 80))
        readMoreButton.setAttributedTitle(NSAttributedString(string: Strings.readMoreButtonTitle, attributes: Fonts.featureButtonText), forState: UIControlState.Normal)
        //readMoreButton.addTarget(self, action: "readArticle", forControlEvents: .TouchUpInside)
        readMoreButton.layer.cornerRadius = 6
        readMoreButton.layer.borderColor = UIColor.whiteColor().CGColor
        readMoreButton.layer.borderWidth = 1
        readMoreButton.center.x = pageView.center.x
        pageView.addSubview(readMoreButton)

        println(i)

        scrollView.addSubview(pageView)
}

一切都按其应有的方式运行，除了当我尝试为新按钮分配标题时，循环变成了无限循环。如果我打印出循环的当前索引，它会不断循环。示例:

0
1
2
0
1
2
0
1
2

如果我注释掉 myButton.setTitle() 方法，问题就会消失，索引打印如下:

0
1
2

我尝试过setTitle和setAttributedTitle，两者效果是一样的。我尝试过调度不同的队列，但似乎没有任何效果。

同样，一切都适用于背景图像、两个标签、 View 等。仅当将按钮混合在一起时才存在问题。即使我删除 FileStoreManager 代码，该问题仍然存在。

for 循环中的按钮有些不愉快。

<小时/>

编辑#1

我决定尝试创建一个新项目，只是为了在 for 循环中测试按钮创建。这工作得很好。

var x = 20
var y = 20

override func viewDidLoad() {
    super.viewDidLoad()

    for i in 1...10 {
        var myview = UIView(frame: CGRectMake(CGFloat(x), CGFloat(y), 100, 50))
        var button = UIButton(frame: CGRectMake(0, 0, 100, 50))
        button.setTitle("Test", forState: .Normal)
        button.setTitleColor(UIColor.blackColor(), forState: .Normal)
        button.layer.borderColor = UIColor.blackColor().CGColor
        button.layer.borderWidth = 2
        myview.addSubview(button)
        view.addSubview(myview)
        x = x+20
        y = y+20
        println(i)
    }    
}

Answer 1

您还可以尝试快速枚举，以防某些内容在您的范围内出现困惑。

for feature in features { ... }

或者如果您需要索引:

for (index, features) in features.enumerate() { ... }

不确定它会解决问题，但它可能会提高可读性。