对于Swift 3.0 NSBundle不工作，下面的代码工作完美。

let versionNumberString =
      Bundle.main.object(forInfoDictionaryKey: "CFBundleShortVersionString")
          as! String

对于版本号，它是:

let buildNumberString =
      Bundle.main.object(forInfoDictionaryKey: "CFBundleVersion")
          as! String

令人困惑的'CFBundleVersion'是在Xcode General->Identity中输入的构建号。

我也知道这个问题已经有了答案，但我总结了之前的答案:

(*)扩展更新

extension Bundle {
    var releaseVersionNumber: String? {
        return infoDictionary?["CFBundleShortVersionString"] as? String
    }
    var buildVersionNumber: String? {
        return infoDictionary?["CFBundleVersion"] as? String
    }
    var releaseVersionNumberPretty: String {
        return "v\(releaseVersionNumber ?? "1.0.0")"
    }
}

用法:

someLabel.text = Bundle.main.releaseVersionNumberPretty

@Deprecated:旧答案

斯威夫特3.1:

class func getVersion() -> String {
    guard let version = Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String else {
        return "no version info"
    }
    return version
}

对于旧版本:

class func getVersion() -> String {
    if let version = NSBundle.mainBundle().infoDictionary?["CFBundleShortVersionString"] as? String {
        return version
    }
    return "no version info"
}

如果你想设置标签文本或者想在其他地方使用;

self.labelVersion.text = getVersion()

Swift 5更新

这是一个函数，我使用来决定是否显示“应用程序更新”页面或不。它返回版本号，我正在将其转换为Int类型:

if let version: String = Bundle.main.infoDictionary?["CFBundleVersion"] as? String {
        guard let intVersion = Int(version) else { return }
        
        if UserDefaults.standard.integer(forKey: "lastVersion") < intVersion {
            print("need to show popup")
        } else {
            print("Don't need to show popup")
        }
        
        UserDefaults.standard.set(intVersion, forKey: "lastVersion")
    }

如果以前从未使用过，它将返回0，小于当前版本号。若要不向新用户显示这样的屏幕，只需在首次登录后或登录完成时添加构建号。

if let version = Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String {
            self.lblAppVersionValue.text = version
        }

以下是Swift 3.2的更新版本:

extension UIApplication
{
    static var appVersion:String
    {
        if let appVersion = Bundle.main.object(forInfoDictionaryKey: "CFBundleShortVersionString")
        {
            return "\(appVersion)"
        }
        return ""
    }

    static var buildNumber:String
    {
        if let buildNum = Bundle.main.object(forInfoDictionaryKey: kCFBundleVersionKey as String)
        {
            return "\(buildNum)"
        }
        return ""
    }

    static var versionString:String
    {
        return "\(appVersion).\(buildNumber)"
    }
}

针对Swift 4.0

let version = Bundle.main.infoDictionary!["CFBundleShortVersionString"]!
let build = Bundle.main.infoDictionary!["CFBundleVersion"]!