swift - addObject 发生多次相同？

Question

我是 xcode/iOS 开发的 super 新手。我用 objective c 编写了一个教程应用程序，它运行得非常棒。我的下一次尝试是 swift 重写它。

一些非常奇怪的事情正在发生。每次在 xml 文档中找到节点时，“对象”NSMutableArray 都会填充相同的项目。 (而不是追加)。我尝试简单地制作对象:var objects = NSMutableArray() 然后使用 objects.addObject(currentFacility) 但同样的事情发生了。

Log paste 基本上是先登录parser 进入company 节点。然后在 for 循环中，它打印出公司已添加到的对象数组的索引和内容。

我试图删除不相关的代码。但我不确定是什么原因，因此冗长。

class MasterViewController: UITableViewController, NSXMLParserDelegate {
    var detailViewController: DetailViewController? = nil
    var objects = [Facility]()
    var currentFacility = Facility()
    var currentValue = ""
    var counter = 0

    func parser(parser: NSXMLParser!, didStartElement elementName: String!, namespaceURI: String!, qualifiedName qName: String!, attributes attributeDict: [NSObject : AnyObject]!) {
        currentValue = ""
        if(elementName == "Facility") {
            counter += 1
            NSLog("LOG: entered co \(counter) \n")
        }
    }

    func parser(parser: NSXMLParser!, didEndElement elementName: String!, namespaceURI:         String!, qualifiedName qName: String!) {
      //[Code here that correctly catches sub nodes omitted for brevity]
      // finished parsing job - add it to the array
        if(elementName == "Facility") {
            objects.append(currentFacility)

            //var desc = currentFacility.description()
            for index in 0...(self.objects.count - 1) {
                var obPrint = self.objects[index] as Facility
                var desc2 = obPrint.description()
                NSLog("\(desc2) and index is \(index)")
            }
            NSLog("LOG: exited co \(counter) \n")
        }
    }
}

下面的日志粘贴包含 OBJECTS 数组的打印输出，为了便于阅读，删除了一些内容:

parser in DID START document
LOG: entered co 1
ECO FINISHING 5100 INDUSTRIAL BLVD FRIDLEY and index is 0
LOG: exited co 1
LOG: entered co 2
ADVANCED FLEX INC. PLANT 2 3905 CALIFORNIA ST. N.E. COLUMBIA HEIGHTS and index is 0
ADVANCED FLEX INC. PLANT 2 3905 CALIFORNIA ST. N.E. COLUMBIA HEIGHTS and index is 1
LOG: exited co 2
LOG: entered co 3
H. B. FULLER CO. MONARCH DIV. 3900 JACKSON ST. N.E. COLUMBIA HEIGHTS and index is 0
H. B. FULLER CO. MONARCH DIV. 3900 JACKSON ST. N.E. COLUMBIA HEIGHTS and index is 1
H. B. FULLER CO. MONARCH DIV. 3900 JACKSON ST. N.E. COLUMBIA HEIGHTS and index is 2
LOG: exited co 3
more of the same, cut for brevity.
.
.

LOG: exited co 10
LOG: entered co 11
ATLAS MFG. 5250 INDL. BLVD. N.E. FRIDLEY and index is 0
ATLAS MFG. 5250 INDL. BLVD. N.E. FRIDLEY and index is 1
ATLAS MFG. 5250 INDL. BLVD. N.E. FRIDLEY and index is 2
ATLAS MFG. 5250 INDL. BLVD. N.E. FRIDLEY and index is 3
ATLAS MFG. 5250 INDL. BLVD. N.E. FRIDLEY and index is 4
ATLAS MFG. 5250 INDL. BLVD. N.E. FRIDLEY and index is 5
ATLAS MFG. 5250 INDL. BLVD. N.E. FRIDLEY and index is 6
ATLAS MFG. 5250 INDL. BLVD. N.E. FRIDLEY and index is 7
ATLAS MFG. 5250 INDL. BLVD. N.E. FRIDLEY and index is 8
ATLAS MFG. 5250 INDL. BLVD. N.E. FRIDLEY and index is 9
ATLAS MFG. 5250 INDL. BLVD. N.E. FRIDLEY and index is 11
LOG: exited co 11
parser in DID End document

Answer 1

currentFacility 被声明为类本身的属性，并且仅分配给一次(使用其默认值)。此外，Facility 是一个 reference type所以每次你将它附加到数组时，它都会将一个引用附加到同一个实例。

当您更新 currentFacility 的属性时，您正在更新所有附加到数组的属性，因为它们仍然引用相同的东西。

如果你想开始使用一个新的currentFacility，你应该在找到每个节点后或添加到数组后创建一个新实例:

self.currentFacility = Facility()