Xcode 8, Swift 3:

let gAppVersion = Bundle.main.object(forInfoDictionaryKey: "CFBundleShortVersionString") ?? "0"
let gAppBuild = Bundle.main.object(forInfoDictionaryKey: "CFBundleVersion") ?? "0"

extension UIApplication {

    static var appVersion: String {
        if let appVersion = NSBundle.mainBundle().objectForInfoDictionaryKey("CFBundleShortVersionString") {
            return "\(appVersion)"
        } else {
            return ""
        }
    }

    static var build: String {
        if let buildVersion = NSBundle.mainBundle().objectForInfoDictionaryKey(kCFBundleVersionKey as String) {
            return "\(buildVersion)"
        } else {
            return ""
        }
    }

    static var versionBuild: String {
        let version = UIApplication.appVersion
        let build = UIApplication.build

        var versionAndBuild = "v\(version)"

        if version != build {
            versionAndBuild = "v\(version)(\(build))"
        }

        return versionAndBuild
    }

}

注意: 你应该在这里使用if，以防应用程序版本或构建没有设置，这将导致崩溃，如果你尝试使用!打开。

针对Swift 2.0

//First get the nsObject by defining as an optional anyObject

let nsObject: AnyObject? = NSBundle.mainBundle().infoDictionary!["CFBundleShortVersionString"]
let version = nsObject as! String

鉴于Swift一直在发展，我的回答(截至2015年8月):

let version = NSBundle.mainBundle().infoDictionary!["CFBundleVersion"] as! String

if let version = Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String {
        lblVersion.text = "Version \(version)"

    }

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