macOS 应用内更新检查

如果要实现应用内新版本检查，需对应用安装包和版本信息进行托管。这里所举例适用 Github 平台，但检查思路大同小异。总体步骤分为菜单配置、版本信息获取、用户窗口提示、在线下载更新。本文展示代码源自开源项目 NuwaStone 。

配置检查更新菜单

首先需要在菜单栏新增一项菜单，然后关联功能实现方法。如这里在主菜单内新增Check for Updates...菜单。然后在ViewController文件中新增相关响应函数，这里入参类型为NSMenuItem。

添加检查更新菜单

@IBAction func updateMenuItemSelected(_ sender: NSMenuItem) {
}

然后将新增的菜单和函数进行绑定。找到该菜单右上橘黄色的1图标，它表示First Responder，然后右击，在下拉显示的函数中找到刚刚新增的updateMenuItemSelected，然后鼠标移动到函数右侧圆框，等圆框内显示+，单击+并拖动到新增菜单，即可实现菜单和函数绑定，如下图所示。

绑定菜单和响应方法

获取版本信息

首先需要获取应用的当前版本信息和最新版本信息，两者对比即可明确是否需要更新。获取当前应用的版本非常简单，相关信息都会存储到应用包内的info.plist文件中，开发者可通过主Bundle对象获取当前版本信息，代码如下：

@IBAction func updateMenuItemSelected(_ sender: NSMenuItem) {
    let infoDict = Bundle.main.infoDictionary
    let currentVersion = infoDict!["CFBundleShortVersionString"] as! String
}

应用的最新版本信息需通过发布页面获取，这里以 GitHub 托管网站为例进行说明。在对开源项目配置Releases页面后，开发者可在此发布产品（应用）更新，并对当前发布选择一个tag，一般选取的tag为版本号。而且最新的发布会被置为Latest，这意味着我们可以通过访问https://github.com/UserName/ProjectName/releases/latest查看产品的最新版本，访问该链接时，会自动跳转到https://github.com/UserName/ProjectName/releases/tag/YourLatestTag，YourLatestTag即最新的版本号。我们可以据此使用curl -I获取最新的版本信息，命令如下。

➜  ~ curl -I https://github.com/ConradSun/NuwaStone/releases/latest
HTTP/1.1 200 Connection established

HTTP/2 302
server: GitHub.com
date: Mon, 17 Jul 2023 07:09:05 GMT
content-type: text/html; charset=utf-8
vary: X-PJAX, X-PJAX-Container, Turbo-Visit, Turbo-Frame, Accept-Encoding, Accept, X-Requested-With
location: https://github.com/ConradSun/NuwaStone/releases/tag/v2.0
cache-control: no-cache
strict-transport-security: max-age=31536000; includeSubdomains; preload
x-frame-options: deny
x-content-type-options: nosniff
x-xss-protection: 0
......

上面curl -I输出里的location便是跳转后的地址。截取最后一个地址单元，便能获取到最新的版本号，代码如下：

@IBAction func updateMenuItemSelected(_ sender: NSMenuItem) {
    var latestVersion = String()

    guard let result = launchTask(path: "/usr/bin/curl", args: ["-I", "YourUrl"]) else {
        return
    }

    let contentList = result.split(separator: "\r\n")
    for contentItem in contentList {
        if contentItem.contains("location") {
            let tag = contentItem.split(separator: "/").last!
            if tag.first == "v" {
                Logger(.Info, "The latest version is \(tag).")
                latestVersion = tag.dropFirst().lowercased()
            }
        }
    }
}

func launchTask(path: String, args: [String]) -> String? {
    let task = Process()
    let pipe = Pipe()
    task.arguments = args
    task.standardOutput = pipe
    
    if #available(macOS 10.13, *) {
        task.executableURL = URL(fileURLWithPath: path)
        try? task.run()
    } else {
        task.launchPath = path
        task.launch()
    }
    
    var output = Data()
    if #available(macOS 10.15.4, *) {
        guard let value = try? pipe.fileHandleForReading.readToEnd() else {
            return nil
        }
        output = value
    } else {
        output = pipe.fileHandleForReading.readDataToEndOfFile()
    }
    
    guard let result = String(data: output, encoding: .utf8) else {
        return nil
    }
    return result
}

用户提示弹窗

当前应用的版本号和最新的版本号均获取到了，只需比较两个版本号是否相等，便可知道当前版本是否最新，然后对是否需要更新进行弹窗提示。完整代码如下：

@IBAction func updateMenuItemSelected(_ sender: NSMenuItem) {
    let infoDict = Bundle.main.infoDictionary
    let currentVersion = infoDict!["CFBundleShortVersionString"] as! String
    var latestVersion = String()

    let infoView = NSAlert()
    infoView.alertStyle = .informational

    guard let result = launchTask(path: "/usr/bin/curl", args: ["-I", "YourUrl"]) else {
        return
    }

    let contentList = result.split(separator: "\r\n")
    for contentItem in contentList {
        if contentItem.contains("location") {
            let tag = contentItem.split(separator: "/").last!
            if tag.first == "v" {
                Logger(.Info, "The latest version is \(tag).")
                latestVersion = tag.dropFirst().lowercased()
            }
        }
    }

    if latestVersion.isEmpty {
        infoView.alertStyle = .critical
        infoView.messageText = "Error"
        infoView.informativeText = "Failed to get latest info for YourAPPName."
    } else if latestVersion == currentVersion {
        infoView.messageText = "You're up-to-date!"
        infoView.informativeText = "YourAPPName \(currentVersion) is the latest version."
    } else {
        infoView.messageText = "You're out-of-date!"
        infoView.informativeText = "Newer version \(currentVersion) is currently avaliable."
        infoView.addButton(withTitle: "Ignore")
        infoView.addButton(withTitle: "Update")
    }
    let resp = infoView.runModal()
    if resp == .alertSecondButtonReturn {
        let siteAddr = URL(string: "YourProductsUrl")
        NSWorkspace.shared.open(siteAddr!)
    }
}