检测具有先前版本的应用程序的首次启动 [英] Detecting the first launch of an app with previous versions

问题描述

我想更新一个应用，以便在首次启动时添加游览.我通常会用某种 NSUserDefaults 键来处理这个问题.但是，该应用程序的现有版本已经发布.

I would like to update an app to add a tour on first launch. I would ordinarily handle this with some kind of NSUserDefaults key. However, there are pre-existing existing versions of the app already released.

如何在应用首次启动时触发某些行为，但仅适用于全新安装，而不适用于更新后的首次启动?

How can I trigger some behavior on first launch of the app, but only for fresh installs and not for the first launch after an update?

推荐答案

最简单的方法是使用 NSUserDefaults 保存当前版本:

The easiest way is to save the current version using NSUserDefaults:

if (![[NSUserDefaults standardUserDefaults] objectForKey:@"app_version"] || [[[NSUserDefaults standardUserDefaults] objectForKey:@"app_version"] integerValue] < [[[NSBundle mainBundle] objectForInfoDictionaryKey: @"CFBundleVersion"] integerValue]) {
    // new version detected!
    [[NSUserDefaults standardUserDefaults] setObject:[[NSBundle mainBundle] objectForInfoDictionaryKey: @"CFBundleVersion"] forKey:@"app_vervion"];
}

编辑为包含此功能的首次更新添加了对用户默认值存在的检查.

EDIT Added check for user defaults existence for first update containing this functionality.

编辑二我现在明白你真正想要什么.您将需要几乎与我编写的代码相同的代码:

EDIT II I now understood what you really want. You'll need almost the same code I wrote:

if (![[NSUserDefaults standardDefaults] boolForKey:@"tour_done"]) {
    // present tour and that call:
    // [[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"tour_done"];
    // [[NSUserDefaults standardUserDefaults] synchronize];
}

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