Replace `UIScreen.main` to get display scale on iOS 13.0 and later (#2215) #2216

hyun99999 · 2023-10-18T06:23:22Z

UIScree.main will be deprecated in a future version of iOS.
I used window.windowScene.screen to get display's scale.

developer doc > mian already deprecated. It causes serious errors in the near future.

So have to change another way. And window.windowScene.screen is the one way of getting display's scale. That is available from iOS 13.0. This is why control flow has iOS 13.0 condition.

Resolved: #2215

calda · 2023-10-18T13:33:55Z

Sources/Public/iOS/LottieAnimationViewBase.swift

@@ -39,7 +39,11 @@ open class LottieAnimationViewBase: UIView {

  var screenScale: CGFloat {
    #if os(iOS) || os(tvOS)
-    UIScreen.main.scale
+    if #available(iOS 13.0, *) {
+        return window?.windowScene?.screen.scale ?? .zero


Is there a way to provide a reasonable fallback, similar to UIScreen.main.scale, rather than just .zero? Returning .zero for some reason would result in a very broken experience.

UIScreen.main.scale has several values taht each device display.

For Retina displays, the scale factor may be 3.0 or 2.0 and one point can represented by nine or four pixels, respectively. For standard-resolution displays, the scale factor is 1.0 and one point equals one pixel
https://developer.apple.com/documentation/uikit/uiscreen/1617836-scale

Not all devices had a Retina display for the iPhone. This is expected complex control flow.

If there noting special happens, a view will have window.windowScene. However, it seems reasonable to set it to 1.0 to ensure minimal operation through the scale factor.

Related commit history : d3cbc94

Sources/Public/iOS/LottieAnimationViewBase.swift

- add tvOS 13.0 Co-authored-by: Cal Stephens <cal@calstephens.tech>

calda · 2023-10-18T15:55:05Z

Sources/Public/iOS/LottieAnimationViewBase.swift

@@ -39,7 +39,11 @@ open class LottieAnimationViewBase: UIView {

  var screenScale: CGFloat {
    #if os(iOS) || os(tvOS)
-    UIScreen.main.scale
+    if #available(iOS 13.0, tvOS 13.0, *) {
+        return window?.windowScene?.screen.scale ?? 1.0


This will still be a behavior change if window == nil, but I'm not sure if there's a case where that matters (since if window == nil then the view isn't on-screen anyway).

I'm on the same page.

Sources/Public/iOS/LottieAnimationViewBase.swift

hyun99999

Thank you for your review so far.

calda · 2023-10-18T18:58:08Z

This change has reduced the render quality of text in the snapshot tests regression suite. Here's an example:

Before	After

That will need to be fixed before we can merge this, since there could be other consumers using a render configuration similar to our snapshot test suite.

calda

Currently screenScale is only accessed in commonInit(), which is called during init(). At this point view.window is always nil, so screenScale will always be 1.0.

If we're going to access view.window, then we need to handle the case where the window changes, e.g. by rerunning any logic that depends on the window or screenScale in didMoveToWindow.

hyun99999 · 2023-10-19T03:13:50Z

Currently screenScale is only accessed in commonInit(), which is called during init(). At this point view.window is always nil, so screenScale will always be 1.0.

If we're going to access view.window, then we need to handle the case where the window changes, e.g. by rerunning any logic that depends on the window or screenScale in didMoveToWindow.

Implements screenScale setter to re-run action that depend on the screenScale in didMoveToWindow
Related comiit is 5cf3555.

- delete `-` and space.

hyun99999 · 2023-10-19T09:46:09Z

hmm.. window property has nil, until a view is added to window.
Would it be difficult to change Build Setting > Require Only App-Extension-Safe APIvalue to NO?
That can use UIApplication.shared. And this is can access to scale property.
@calda

calda · 2023-10-19T12:44:16Z

I don't think the change you made fixed the problem, because LottieAnimationView itself is accessing screenScale in init (before the view has a window) and then never accesses it again. We'll need to make it so LottieAnimationView itself reacts to screenScale updates. Hopefully this doesn't require completely reinitializing the animation layer, since that would be pretty expensive.

calda · 2023-10-19T12:48:40Z

Require Only App-Extension-Safe APIvalue to NO?

Hmmmmm, this probably would be a breaking change for some number of consumers. Is there a way for us to #if def the check, so we use the simpler code unless in an app extension?

calda · 2023-10-19T12:49:13Z

What would the code look like using UIApplication.shared?

hyun99999 · 2023-10-19T12:57:02Z

What would the code look like using UIApplication.shared?

Like this!

let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene
windowScene?.screen.scale

hyun99999 · 2023-10-19T13:01:27Z

Require Only App-Extension-Safe APIvalue to NO?

Hmmmmm, this probably would be a breaking change for some number of consumers. Is there a way for us to #if def the check, so we use the simpler code unless in an app extension?

I don't understand '#if def the check'. Perdon?

hyun99999 · 2023-10-19T13:03:30Z

CI/Test Package are continuously failed.
Let's commit and see if the test passes or not.

- to use `UIApplication.shared`

calda · 2023-10-19T14:46:23Z

I was thinking something like this: https://stackoverflow.com/questions/25048026/how-to-detect-if-code-is-running-in-main-app-or-app-extension-target but it sounds like this won't be possible for us since (1) we don't control the custom build flags, and (2) we distribute pre-compiled binaries. So I don't think we can use UIApplication.shared unfortunately.

hyun99999 · 2023-10-20T06:44:22Z

I was thinking something like this: https://stackoverflow.com/questions/25048026/how-to-detect-if-code-is-running-in-main-app-or-app-extension-target but it sounds like this won't be possible for us since (1) we don't control the custom build flags, and (2) we distribute pre-compiled binaries. So I don't think we can use UIApplication.shared unfortunately.

Recently i access screenScale in didMoveToWindow() but it is not apply layer screen scale in commonInit(). I agree your opinion.
Then i'll have to look for it that LottieAnimationView updates screenScale itself. After view is added that it has window.

Sources/Public/iOS/LottieAnimationViewBase.swift

Co-authored-by: Cal Stephens <cal@calstephens.tech>

calda · 2023-11-02T13:30:45Z

Thanks!

hyun99999 · 2023-11-02T13:35:13Z

Thank you for your sincere review! 🙌

This PR contains the following updates: | Package | Update | Change | |---|---|---| | [airbnb/lottie-spm](https://togithub.com/airbnb/lottie-spm) | patch | `from: "4.3.3"` -> `from: "4.3.4"` | --- ### Release Notes <details> <summary>airbnb/lottie-spm (airbnb/lottie-spm)</summary> ### [`v4.3.4`](https://togithub.com/airbnb/lottie-spm/releases/tag/4.3.4) [Compare Source](https://togithub.com/airbnb/lottie-spm/compare/4.3.3...4.3.4) #### What's Changed - Fix parsing regression in 4.3.0 from addition of parsing layer effects by [@calda](https://togithub.com/calda) in [airbnb/lottie-ios#2208 - Remove old animation layer when creating a new animation layer by [@junjielu](https://togithub.com/junjielu) in [airbnb/lottie-ios#2214 - Add configuration setting to remove animated bounds changes by [@thedrick](https://togithub.com/thedrick) in [airbnb/lottie-ios#2218 - Change pod dependencies `SwiftUI` and `Combine` to `weak` to ensure compatibility with iOS 12 by [@florianrhein](https://togithub.com/florianrhein) in [airbnb/lottie-ios#2219 - Fix issue where Repeater would be ignored if not at top level by [@calda](https://togithub.com/calda) in [airbnb/lottie-ios#2221 - Replace `UIScreen.main` to get display scale on iOS 13.0 and later ([#2215](https://togithub.com/airbnb/lottie-spm/issues/2215)) by [@hyun99999](https://togithub.com/hyun99999) in [airbnb/lottie-ios#2216 - Dispatch dot lottie file loading onto a single serial queue by [@erichoracek](https://togithub.com/erichoracek) in [airbnb/lottie-ios#2229 - Clean up unused property in InvertedMatteLayer by [@hanton](https://togithub.com/hanton) in [airbnb/lottie-ios#2241 - Fix issue where LottieView animation would restart from beginning after backgrounding app by [@calda](https://togithub.com/calda) in [airbnb/lottie-ios#2237 **Full Changelog**: airbnb/lottie-ios@4.3.3...4.3.4 </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Enabled. ♻ **Rebasing**: Whenever PR is behind base branch, or you tick the rebase/retry checkbox. 👻 **Immortal**: This PR will be recreated if closed unmerged. Get [config help](https://togithub.com/renovatebot/renovate/discussions) if that's undesired. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Renovate Bot](https://togithub.com/renovatebot/renovate).  Co-authored-by: Self-hosted Renovate Bot <361546+cgrindel-self-hosted-renovate[bot]@users.noreply.github.enterprise.com>

…IScreen.main.scale` (airbnb#2216) Co-authored-by: Cal Stephens <cal@calstephens.tech>

Use UIApplication instead of UIScreen.main on iOS 13.0 and later

e7c46c5

hyun99999 changed the title ~~Use UIApplication instead of UIScreen.main on iOS 13.0 and later~~ Use UIApplication instead of UIScreen.main on iOS 13.0 and later (#2215) Oct 18, 2023

Use window.windowScene.screen instead of UIScreen.main

634316d

hyun99999 changed the title ~~Use UIApplication instead of UIScreen.main on iOS 13.0 and later (#2215)~~ Use window.windowScene.screen instead of UIScreen.main on iOS 13.0 and later (#2215) Oct 18, 2023

calda reviewed Oct 18, 2023

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Sources/Public/iOS/LottieAnimationViewBase.swift Outdated Show resolved Hide resolved

hyun99999 and others added 2 commits October 18, 2023 22:54

Update control flow

db7be79

- add tvOS 13.0 Co-authored-by: Cal Stephens <cal@calstephens.tech>

Fix .zero to 1.0 ensure minimal operation through the scale factor.

d3cbc94

hyun99999 force-pushed the master branch from be10a85 to d3cbc94 Compare October 18, 2023 15:41

calda reviewed Oct 18, 2023

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calda approved these changes Oct 18, 2023

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calda enabled auto-merge (squash) October 18, 2023 15:55

calda reviewed Oct 18, 2023

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Sources/Public/iOS/LottieAnimationViewBase.swift Outdated Show resolved Hide resolved

Update Sources/Public/iOS/LottieAnimationViewBase.swift

ff2e189

hyun99999 commented Oct 18, 2023

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calda self-requested a review October 18, 2023 18:56

calda requested changes Oct 18, 2023

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Implement screenScale setter to reassign scale value

5cf3555

auto-merge was automatically disabled October 19, 2023 03:09
Head branch was pushed to by a user without write access

hyun99999 added 3 commits October 19, 2023 12:18

Fix to comply code format

fcb4e4c

- delete `-` and space.

Add for explicit return

a45f723

Use UIApplication instead of UIScreen.main

c7c3326

Update APPLICATION_EXTENSION_API_ONLY value

b5d53d6

- to use `UIApplication.shared`

hyun99999 added 3 commits October 20, 2023 17:14

Update APPLICATION_EXTENSION_API_ONLY value

bbc97c7

Use UITraitCollection to access display scale

8b75d16

Fix to comply code format

62c5fad

calda reviewed Nov 1, 2023

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hyun99999 changed the title ~~Use window.windowScene.screen instead of UIScreen.main on iOS 13.0 and later (#2215)~~ Replace UIScreen.main to get display scale on iOS 13.0 and later (#2215) Nov 2, 2023

Ensure displayScale value that guarantees 1 or more

5302ad6

Co-authored-by: Cal Stephens <cal@calstephens.tech>

calda approved these changes Nov 2, 2023

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calda merged commit f081afa into airbnb:master Nov 2, 2023
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ElonPark mentioned this pull request Jan 12, 2024

fix: fix getDisplayScale layoutBox/PinLayout#279

Merged

iago849 pushed a commit to atteamapps/lottie-ios that referenced this pull request Feb 8, 2024

Use UITraitCollection.current.displayScale instead of deprecated `U…

4dbf517

…IScreen.main.scale` (airbnb#2216) Co-authored-by: Cal Stephens <cal@calstephens.tech>

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Replace `UIScreen.main` to get display scale on iOS 13.0 and later (#2215) #2216

Replace `UIScreen.main` to get display scale on iOS 13.0 and later (#2215) #2216

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Replace UIScreen.main to get display scale on iOS 13.0 and later (#2215) #2216

Replace UIScreen.main to get display scale on iOS 13.0 and later (#2215) #2216

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Replace `UIScreen.main` to get display scale on iOS 13.0 and later (#2215) #2216

Replace `UIScreen.main` to get display scale on iOS 13.0 and later (#2215) #2216

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