看过文档后，我认为以下内容更清晰:

let version = 
NSBundle.mainBundle().objectForInfoDictionaryKey("CFBundleShortVersionString") 
as? String

来源: 使用此方法优于其他访问方法，因为它在键可用时返回键的本地化值。

EDIT

Swift 4.2更新

let appVersion = Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String

EDIT

正如@azdev在Xcode的新版本上指出的那样，你会得到一个编译错误，尝试我以前的解决方案，要解决这个问题，只需编辑它，建议使用一个打开包字典!

let nsObject: AnyObject? = Bundle.main.infoDictionary!["CFBundleShortVersionString"]

最后编辑

使用与Objective-C中相同的逻辑，但有一些小的变化

//First get the nsObject by defining as an optional anyObject
let nsObject: AnyObject? = NSBundle.mainBundle().infoDictionary["CFBundleShortVersionString"]

//Then just cast the object as a String, but be careful, you may want to double check for nil
let version = nsObject as! String

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()

现在您可以使用常量来实现这一点，而不必像以前那样使用字符串类型的代码，这使得事情变得更加方便。

var appVersion: String {
    return Bundle.main.infoDictionary![kCFBundleVersionKey as String] as! String
}

public var appVersionNumberString: String {
    get {
        return Bundle.main.object(forInfoDictionaryKey: "CFBundleShortVersionString") as! String
    }
}

我为UIApplication创建了一个扩展。

extension UIApplication {
    static var appVersion: String {
        let versionNumber = Bundle.main.infoDictionary?[IdentifierConstants.InfoPlist.versionNumber] as? String
        let buildNumber = Bundle.main.infoDictionary?[IdentifierConstants.InfoPlist.buildNumber] as? String
        
        let formattedBuildNumber = buildNumber.map {
            return "(\($0))"
        }

        return [versionNumber,formattedBuildNumber].compactMap { $0 }.joined(separator: " ")
    }
}

enum Constants {
    enum InfoPlist {
        static let versionNumber = "CFBundleShortVersionString"
        static let buildNumber = "CFBundleVersion"
    }
}