Swift：String 内的 Int 增量问题

Question

我正在尝试增加 String 内的 Int 值，但我不明白为什么增加只会发生一次！这是代码：

class DownloadFile : NSObject {

  var number = 1
init(url : String) {

    urlOfDownload = url
    fileUrl = URL(string: url)!


    //Added by me , checks if file is already exist try to add new file name
    let path = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first! as String
    let url = NSURL(fileURLWithPath: path)
    let filePath = url.appendingPathComponent(fileUrl.lastPathComponent)!.path
    let fileManager = FileManager.default
    if fileManager.fileExists(atPath: filePath) {


            number += 1

        print("FILE AVAILABLE")
        nameOfDownload = "\(fileUrl.deletingPathExtension().lastPathComponent)\(number).\(fileUrl.pathExtension)"

    } else {

        print("FILE NOT AVAILABLE")
        nameOfDownload = fileUrl.lastPathComponent
    }

}

}

使用类：

let downloadFile = DownloadFile(url: url)
    downloadFile.startDownload()

Answer 1

你需要让你的varstatic在类实例之间共享它：

class DownloadFile : NSObject {

    static var number = 1
    init(url : String) {
        ...
        DownloadFile.number += 1
        ...
    }
}