比较具有格式“2.0.1”，“2.0.09”的字符串， [英] Comparing strings with the format "2.0.1", "2.0.09"

问题描述

我需要获取用户的应用版本号，并将其与我服务器上的当前应用版本进行比较。如果用户的应用程序版本较低，他会得到一个弹出窗口来更新他的应用程序。在执行此操作时，我需要比较应用程序的版本与可用的版本。如何比较格式2.0.1和2.0.09的字符串，并得到最高的一个，在Objective-C？

I need to get the user's app version number and compare it with the current app version on my server. If the user's app version is lower, then he will get a pop-up to update his app. While doing this, I need to compare the version of the app with the versions that are available. How can I compare the strings which are in the format "2.0.1" and "2.0.09" and get the highest one, in Objective-C?

推荐答案

如果你的字符串都是2.0.1可以只使用正确的选项进行比较：

If your strings are all of the form "2.0.1" etc. you can just compare them as is with the right options:

([localVersionString compare:currentVersionString
                     options:NSNumericSearch] != NSOrderedAscending);

上述会返回 YES if localVersion不早于服务器上的currentVersion，否则为 NO （假设我有正确的方式）。

The above would return "YES" if the localVersion is no older than the currentVersion on the server, and "NO" otherwise (assuming I have this the right way round).

这是在检查安装在iDevice上的iOS的本地版本时通常要做的事情。

This is the usual thing to do when checking the local version of iOS installed on an iDevice.

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