如何在Swift 3中使用自定义URL方案打开iOS App？

Question

I need to open my particular UIViewController when the following link is clicked on the Safari browser:

http://my.sampledomain.com/en/customer/account/resetpassword/?id=24&token=8fbf662617d14c10f4a11f716c1b2285

When this link is clicked on the browser, I need to open my application on a particular screen and retrieve the data from this url. For example:

id = 24
token = 8fbf662617d14c10f4a11f716c1b2285

...and pass it to that particular UIViewController.

How can i do that?

Answer 1

What you are describing is called Deep Linking . It's a very common app feature to implement — most apps have it — and conceptually, it seems like an easy thing to build. However, it's complicated to get right, and there are a lot of edge cases.

You basically need to accomplish two things:

1. If the app is installed: open the app and route users to the correct content inside it.
2. If the app is NOT installed: forward users to the App Store so they can download it. Ideally, also route users to the correct content inside the app after downloading (this is known as 'deferred deep linking').

While not required, you'll also probably want to track all of this activity so you can see what is working.

If the app is installed

Your existing custom URI scheme fits into this category. However, Apple has decided that custom URI schemes are not a good technology, and deprecated them with iOS 9 in favor of Universal Links .

Apple is right about this. Custom URI schemes have a number of problems, but these are the biggest:

• There is no fallback if the app isn't installed. In fact, you get an error.
• They often aren't recognized as links the user can click.

To work around these, it used to be possible to use a regular http:// link, and then insert a redirect on the destination page to forward the user to your custom URI scheme, thereby opening the app. If that redirect failed, you could then redirect users to the App Store instead, seamlessly. This is the part Apple broke in iOS 9 to drive adoption of Universal Links.

Universal Links are a better user experience, because they are http:// links by default and avoid nasty errors. However, they are hard to set up and still don't work everywhere .

To ensure your users end up inside the app when they have it installed, you need to support both Universal Links and a custom URI scheme, and even then there are a lot of edge cases like Facebook and Twitter which require special handling.

If the app is NOT installed

In this case, the user will end up on your http:// fallback URL. At this point, you have two options:

1. Immediately forward the user directly to the App Store.
2. Send the user to your mobile website (and then use something like a smart banner to give them the option of going to the App Store).

Most large brands prefer the second option. Smaller apps often go with the first approach, especially if they don't have a website.

To forward the user to the App Store, you can use a Javascript redirect like this:

<script type="text/javascript">
  window.onload = function() {
    window.location = "https://itunes.apple.com/app/id1121012049";
  };
</script>

Until recently, it was possible to use a HTTP redirect for better speed, but Apple changed some behavior in Safari with iOS 10.3 , so this no longer works as well.

Deferred deep linking

Unfortunately there's no native way to accomplish this last piece on either iOS or Android. To make this work, you need a remote server to close the loop. You can build this yourself , but you really shouldn't for a lot of reasons, not the least of which being you have more important things to do.

Bottom line

Deep linking is very complicated. Most apps today don't attempt to set it up by building an in-house system. Free hosted deep link services like Branch.io (full disclosure: they're so awesome I work with them) and Firebase Dynamic Links can handle all of this for you, and ensure you are always up to date with the latest standards and edge cases.

See here for a video overview an employee at Branch made of everything you need to know about this.