我知道这个问题已经有人回答了，但我个人认为这个问题更清晰一些:

斯威夫特3.0:

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

斯威夫特< 2.3

if let version = NSBundle.mainBundle().infoDictionary?["CFBundleShortVersionString"] as? String {
    self.labelVersion.text = version
}

这样，if let版本就负责条件处理(在我的例子中设置标签文本)，如果infoDictionary或CFBundleShortVersionString为nil，则可选的展开将导致代码被跳过。

Swift 5作为UIApplication扩展

extension UIApplication {
    static var release: String {
        return Bundle.main.object(forInfoDictionaryKey: "CFBundleShortVersionString") as! String? ?? "x.x"
    }
    static var build: String {
        return Bundle.main.object(forInfoDictionaryKey: "CFBundleVersion") as! String? ?? "x"
    }
    static var version: String {
        return "\(release).\(build)"
    }
}

使用示例:

print("release: \(UIApplication.release)")
print("build: \(UIApplication.build)")
print("version: \(UIApplication.version)")

斯威夫特5.3

let infoDictionaryKey = kCFBundleVersionKey as String
guard let currentVersion = Bundle.main.object(forInfoDictionaryKey: infoDictionaryKey) as? String
else { fatalError("Expected to find a bundle version in the info dictionary") }

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

斯威夫特4

//首先通过定义一个可选的AnyObject来获取nsObject

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

//然后将对象转换为String，但要小心，你可能需要再次检查是否为nil

let version = nsObject 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"
    }
}