Follow up to #3187.
Thanks to @charliemchapman for reporting.

`IntroEligibilityViewModel` was being recreated, which meant that we were losing the internal state on redraws.

I've also simplified the initialization of `TrialOrIntroEligibilityChecker` and `PurchaseHandler` to avoid duplicated calls to `.default()`

Follow up to #3187.
Thanks to @charliemchapman for reporting.

`IntroEligibilityViewModel` was being recreated, which meant that we
were losing the internal state on redraws.

I've also simplified the initialization of
`TrialOrIntroEligibilityChecker` and `PurchaseHandler` to avoid
duplicated calls to `.default()`.

…nstances (#3187)

This was breaking event notifications as well as
`OnPurchaseCompletedModifier`, because there were multiple
`PurchaseHandler` instances created.

The solution is to make `PaywallView` store these as `@StateObject`. In
order to do that, the type can't be optional, so I instead encoded the
"is configured" information inside.

Follow up to #3187.
Thanks to @charliemchapman for reporting.

`IntroEligibilityViewModel` was being recreated, which meant that we
were losing the internal state on redraws.

I've also simplified the initialization of
`TrialOrIntroEligibilityChecker` and `PurchaseHandler` to avoid
duplicated calls to `.default()`.

…nstances (#3187)

This was breaking event notifications as well as
`OnPurchaseCompletedModifier`, because there were multiple
`PurchaseHandler` instances created.

The solution is to make `PaywallView` store these as `@StateObject`. In
order to do that, the type can't be optional, so I instead encoded the
"is configured" information inside.

Follow up to #3187.
Thanks to @charliemchapman for reporting.

`IntroEligibilityViewModel` was being recreated, which meant that we
were losing the internal state on redraws.

I've also simplified the initialization of
`TrialOrIntroEligibilityChecker` and `PurchaseHandler` to avoid
duplicated calls to `.default()`.

…nstances (#3187)

This was breaking event notifications as well as
`OnPurchaseCompletedModifier`, because there were multiple
`PurchaseHandler` instances created.

The solution is to make `PaywallView` store these as `@StateObject`. In
order to do that, the type can't be optional, so I instead encoded the
"is configured" information inside.

Follow up to #3187.
Thanks to @charliemchapman for reporting.

`IntroEligibilityViewModel` was being recreated, which meant that we
were losing the internal state on redraws.

I've also simplified the initialization of
`TrialOrIntroEligibilityChecker` and `PurchaseHandler` to avoid
duplicated calls to `.default()`.

…nstances (#3187)

This was breaking event notifications as well as
`OnPurchaseCompletedModifier`, because there were multiple
`PurchaseHandler` instances created.

The solution is to make `PaywallView` store these as `@StateObject`. In
order to do that, the type can't be optional, so I instead encoded the
"is configured" information inside.

Follow up to #3187.
Thanks to @charliemchapman for reporting.

`IntroEligibilityViewModel` was being recreated, which meant that we
were losing the internal state on redraws.

I've also simplified the initialization of
`TrialOrIntroEligibilityChecker` and `PurchaseHandler` to avoid
duplicated calls to `.default()`.

**This is an automatic release.**
### New Features
#### ✨ Introducing RevenueCatUI 📱

RevenueCat's Paywalls allow you to to remotely configure your entire
paywall view without any code changes or app updates.
Our paywall templates use native code to deliver smooth, intuitive
experiences to your customers when you’re ready to deliver them an
Offering; and you can use our Dashboard to pick the right template and
configuration to meet your needs.

To use RevenueCat Paywalls on iOS, simply:

1. Create a Paywall on the Dashboard for the `Offering` you intend to
serve to your customers
2. Add the `RevenueCatUI` SPM dependency to your project
3. `import RevenueCatUI` at the point in the user experience when you
want to display a paywall:

```swift
import RevenueCatUI
import SwiftUI

struct YourApp: View {

    var body: some View {
        YourContent()
            .presentPaywallIfNeeded(
                requiredEntitlementIdentifier: "pro",
                purchaseCompleted: { customerInfo in
                    print("Purchase completed: \(customerInfo)")
                },
                restoreCompleted: { customerInfo in
                    print("Purchases restored: \(customerInfo)")
                }
            )
    }

}
```

You can find more information in [our
documentation](https://rev.cat/paywalls).

<details>

<summary>List of changes</summary>
* NachoSoto: `Paywalls`: renamed `PaywallEvent.view` to `.impression`
(#3212)
* NachoSoto: `Paywalls`: loading indicator for in-progress purchases
(#3217)
*  NachoSoto: `Paywalls`: fixed template 4 bottom padding (#3211)
* NachoSoto: `Paywalls`: only pre-warm images/intro-eligibility for
`Offerings.current` (#3210)
* NachoSoto: `Paywalls`: fixed mock intro eligibility on snapshot tests
(#3205)
*  NachoSoto: `Paywalls`: fixed SimpleApp release build (#3203)
*  NachoSoto: `Paywalls`: improved `DebugErrorView` layout (#3204)
* NachoSoto: `Paywalls`: refactored `PurchaseHandler` extracting
protocol (#3196)
*  NachoSoto: `Paywalls`: automatically flush events (#3177)
* NachoSoto: `Paywalls`: fixed `TemplateBackgroundImageView` aspect
ratio (#3201)
*  NachoSoto: `Paywalls`: fixed broken layout on template 4 (#3202)
*  NachoSoto: `Paywalls`: events unit and integration tests (#3169)
*  NachoSoto: `Paywalls`: send events to `Purchases` (#3164)
*  NachoSoto: `Paywalls`: convert empty images into `nil` (#3195)
*  NachoSoto: `Paywalls`: new `onRestoreCompleted` handler (#3190)
* NachoSoto: `Paywalls`: fixed `IntroEligibilityViewModel` data lifetime
(#3194)
* NachoSoto: `Paywalls`: test plan for running non-snapshot tests
(#3188)
*  NachoSoto: `Paywalls`: polish template 4 (#3183)
* NachoSoto: `Paywalls`: fixed data flow resulting in multiple
`PurchaseHandler` instances (#3187)
* Cesar de la Vega: `Paywalls`: update `blurred_background_image` key in
`PaywallData` test fixture (#3186)
*  NachoSoto: `Paywalls`: added `Purchases.track(paywallEvent:)` (#3160)
* NachoSoto: `Paywalls`: don't apply dark appearance with no dark mode
colors (#3184)
* NachoSoto: `Paywalls`: fixed template 2 + `.condensedFooter` + iPad
(#3185)
* NachoSoto: `Paywalls`: new `{{ sub_duration_in_months }}` variable
(#3173)
*  NachoSoto: `Paywalls`: created `PaywallEventsManager` (#3159)
* NachoSoto: `Paywalls`: implemented `PostPaywallEventsOperation`
(#3158)
* NachoSoto: `Paywalls`: new `{{ sub_relative_discount }}` variable
(#3131)
*  Charlie Chapman: `Paywalls`: improved `FooterView` (#3171)
* NachoSoto: `Paywalls`: fixed `FooterView` horizontal centering (#3172)
*  NachoSoto: `Paywalls`: created `PaywallEventStore` (#3157)
*  NachoSoto: `Paywalls`: add `PaywallEvent` model (#3156)
*  NachoSoto: `Paywalls`: add `PaywallData.revision` (#3155)
* NachoSoto: `Paywalls`: support fuzzy-Locale search in `iOS 15` (#3162)
* NachoSoto: `PaywallData`: added `@NonEmptyString` to `subtitle` and
`offerName` (#3150)
* NachoSoto: `Paywalls`: add paywall for Load Shedder integration tests
(#3151)
* NachoSoto: `Paywalls`: fixed error view being displayed on release
builds (#3141)
* NachoSoto: `Paywalls`: improved `{{ total_price_and_per_month }}` to
include period (#3136)
* NachoSoto: `Paywalls`: `{{ price_per_period }}` now takes
`SubscriptionPeriod.value` into account (#3133)
*  NachoSoto: `Paywalls`: add Arabic to SimpleApp for testing (#3132)
* NachoSoto: `Paywalls`: update snapshot generation with new separate
git repo (#3116)
*  NachoSoto: `Paywalls`: add support for CTA button gradients (#3121)
*  NachoSoto: `Paywalls`: template 5 (#3095)
* NachoSoto: `Paywalls`: replaced submodule with `gitignore`d reference
(#3125)
* NachoSoto: `Catalyst`: fixed a couple of Catalyst build warnings
(#3120)
* NachoSoto: `Paywalls`: reference test snapshots from submodule (#3115)
*  NachoSoto: `Paywalls`: removed `presentedPaywallViewMode` (#3109)
* NachoSoto: `Paywalls`: remove duplicate `RevenueCat` scheme to fix
Carthage (#3105)
*  NachoSoto: `Paywalls`: fixed iOS 12 build (#3104)
*  NachoSoto: `Paywalls`: fixed template 2 inconsistent spacing (#3091)
*  NachoSoto: `Paywalls`: improved test custom paywall (#3089)
*  NachoSoto: `Paywalls`: avoid warming up cache multiple times (#3068)
*  NachoSoto: `Paywalls`: added all localization (#3080)
* NachoSoto: `Paywalls`: temporarily disable `PaywallTemplate.template4`
(#3088)
*  NachoSoto: `Paywalls`: enabled `Catalyst` support (#3087)
*  NachoSoto: `Paywalls`: iPad polish (#3061)
*  NachoSoto: `Paywalls`: added MIT license to all headers (#3084)
* NachoSoto: `Paywalls`: improved unselected package background color
(#3079)
*  NachoSoto: `Paywalls`: handle already purchased state (#3046)
* NachoSoto: `Paywalls`: only dismiss `PaywallView` when explicitly
presenting it with `.presentPaywallIfNeeded` (#3075)
* NachoSoto: `Paywalls`: add support for generating snapshots on CI
(#3055)
* NachoSoto: `Paywalls`: removed unnecessary `PaywallFooterView` (#3064)
* Josh Holtz: `Paywalls`: new `PaywallFooterView` to replace `modes`
(#3051)
*  Josh Holtz: `Paywalls`: rename card to footer (#3049)
* NachoSoto: `Paywalls`: changed `total_price_and_per_month` to include
period (#3044)
* NachoSoto: `Paywalls`: internal documentation for implementing
templates (#3053)
*  NachoSoto: `Paywalls`: finished `iOS 15` support (#3043)
* NachoSoto: `Paywalls`: validate `PaywallData` to ensure displayed data
is always correct (#3019)
* NachoSoto: `Paywalls`: fixed `total_price_and_per_month` for custom
monthly packages (#3027)
*  NachoSoto: `Paywalls`: tweaking colors on template 2&3 (#3011)
*  NachoSoto: `Paywalls`: changed snapshots to scale 1 (#3016)
* NachoSoto: `Paywalls`: replaced `defaultLocale` with
`preferredLocales` (#3003)
* NachoSoto: `Paywalls`: improved `PaywallDisplayMode.condensedCard`
layout (#3001)
*  NachoSoto: `Paywalls`: `.card` and `.condensedCard` modes (#2995)
*  NachoSoto: `Paywalls`: prevent multiple concurrent purchases (#2991)
*  NachoSoto: `Paywalls`: improved variable warning (#2984)
*  NachoSoto: `Paywalls`: fixed horizontal padding on template 1 (#2987)
* NachoSoto: `Paywalls`: changed `FooterView` to always use `text1`
color (#2992)
*  NachoSoto: `Paywalls`: retry test failures (#2985)
* NachoSoto: `Paywalls`: send presented `PaywallViewMode` with purchases
(#2859)
*  NachoSoto: `Paywalls`: added support for custom fonts (#2988)
* NachoSoto: `Paywalls`: improved template 2 unselected packages (#2982)
* Josh Holtz: `Paywalls`: fix template 2 selected text offer details
color (#2975)
*  NachoSoto: `Paywalls`: warm-up image cache (#2978)
*  NachoSoto: `Paywalls`: extracted `PaywallCacheWarming` (#2977)
*  NachoSoto: `Paywalls`: fixed color in template 3 (#2980)
*  NachoSoto: `Paywalls`: improved default template (#2973)
*  NachoSoto: `Paywalls`: added links to documentation (#2974)
*  NachoSoto: `Paywalls`: updated template names (#2971)
*  NachoSoto: `Paywalls`: updated variable names (#2970)
* NachoSoto: `Paywalls`: added JSON debug screen to
`debugRevenueCatOverlay` (#2972)
*  NachoSoto: `Paywalls`: multi-package horizontal template  (#2949)
*  NachoSoto: `Paywalls`: fixed template 3 icon aspect ratio (#2969)
*  NachoSoto: `Paywalls`: iOS 17 tests on CI (#2955)
*  NachoSoto: `Paywalls`: deploy `debug` sample app (#2966)
*  NachoSoto: `Paywalls`: sort offerings list in sample app (#2965)
*  NachoSoto: `Paywalls`: initial iOS 15 support (#2933)
* NachoSoto: `Paywalls`: changed default `PaywallData` to display
available packages (#2964)
*  NachoSoto: `Paywalls`: changed `offerDetails` to be optional (#2963)
*  NachoSoto: `Paywalls`: markdown support (#2961)
*  NachoSoto: `Paywalls`: updated icon set to match frontend (#2962)
*  NachoSoto: `Paywalls`: added support for `PackageType.custom` (#2959)
* NachoSoto: `Paywalls`: fixed `tvOS` compilation by making it
explicitly unavailable (#2956)
* NachoSoto: `Paywalls`: fix crash when computing localization with
duplicate packages (#2958)
*  NachoSoto: `Paywalls`: UIKit `PaywallViewController` (#2934)
* NachoSoto: `Paywalls`: `presentPaywallIfNecessary` ->
`presentPaywallIfNeeded` (#2953)
* NachoSoto: `Paywalls`: added support for custom and lifetime products
(#2941)
* NachoSoto: `Paywalls`: changed `SamplePaywallsList` to work offline
(#2937)
* NachoSoto: `Paywalls`: fixed header image mask on first template
(#2936)
*  NachoSoto: `Paywalls`: new `subscription_duration` variable (#2942)
* NachoSoto: `Paywalls`: removed `mode` parameter from
`presentPaywallIfNecessary` (#2940)
*  NachoSoto: `Paywalls`: improved `RemoteImage` error layout (#2939)
* NachoSoto: `Paywalls`: added default close button when using
`presentPaywallIfNecessary` (#2935)
* NachoSoto: `Paywalls`: added ability to preview templates in a
`.sheet` (#2938)
*  NachoSoto: `Paywalls`: avoid recomputing variable `Regex` (#2944)
*  NachoSoto: `Paywalls`: improved `FooterView` scaling (#2948)
* NachoSoto: `Paywalls`: added ability to calculate and localize
subscription discounts (#2943)
*  NachoSoto: `Offering`: improved description (#2912)
*  NachoSoto: `Paywalls`: fixed `FooterView` color in template 1 (#2951)
*  NachoSoto: `Paywalls`: fixed `View.scrollableIfNecessary` (#2947)
* NachoSoto: `Paywalls`: improved `IntroEligibilityStateView` to avoid
layout changes (#2946)
* NachoSoto: `Paywalls`: updated offerings snapshot with new asset base
URL (#2950)
* NachoSoto: `Paywalls`: extracted `TemplateBackgroundImageView` (#2945)
*  NachoSoto: `Paywalls`: more polish from design feedback (#2932)
*  NachoSoto: `Paywalls`: more unit tests for purchasing state (#2931)
*  NachoSoto: `Paywalls`: new `.onPurchaseCompleted` modifier (#2930)
* NachoSoto: `Paywalls`: fixed `LoadingPaywallView` displaying a
progress view (#2929)
* NachoSoto: `Paywalls`: added default template to `SamplePaywallsList`
(#2928)
*  NachoSoto: `Paywalls`: added a few more logs (#2927)
*  NachoSoto: `Paywalls` added individual previews for templates (#2924)
*  NachoSoto: `Paywalls`: improved default paywall configuration (#2926)
* NachoSoto: `Paywalls`: moved purchasing state to `PurchaseHandler`
(#2923)
*  NachoSoto: `Paywalls`: updated Integration Test snapshot (#2921)
* NachoSoto: `Paywalls`: pre-warm intro eligibility in background thread
(#2925)
*  NachoSoto: `Paywalls`: removed "couldn't find package" log (#2922)
* NachoSoto: `Paywalls`: SimpleApp reads API key from Xcode Cloud
environment (#2919)
* NachoSoto: `Paywalls`: improved template accessibility support (#2920)
* NachoSoto: `Paywalls`: work around SwiftUI bug to allow embedding
`PaywallView` inside `NavigationStack` (#2918)
*  NachoSoto: `Paywalls`: some basic polish from design feedback (#2917)
* NachoSoto: `Paywalls`: added `OfferingsList` to preview all paywalls
(#2916)
* NachoSoto: `Paywalls`: fixed tappable area for a couple of buttons
(#2915)
*  NachoSoto: `Paywalls`: new `text1` and `text2` colors (#2903)
* NachoSoto: `Paywalls`: updated multi-package bold template design
(#2908)
*  NachoSoto: `Paywalls`: added sample paywalls to `SimpleApp` (#2907)
*  NachoSoto: `Paywalls`: one package with features template (#2902)
*  NachoSoto: `Paywalls`: initial support for icons (#2882)
* NachoSoto: `Paywalls`: extracted intro eligibility out of templates
(#2901)
*  NachoSoto: `Paywalls`: changed `subtitle` to be optional (#2900)
* NachoSoto: `Paywalls`: added "features" to `LocalizedConfiguration`
(#2899)
* NachoSoto: `Paywalls`: fixed `{{ total_price_and_per_month }}` (#2881)
*  NachoSoto: `Paywalls`: updated template names (#2878)
*  NachoSoto: `Paywalls`: added accent colors (#2883)
* NachoSoto: `Paywalls`: changed images representation to an object
(#2875)
*  NachoSoto: `Paywalls`: added `offerName` parameter (#2877)
*  NachoSoto: `Paywalls`: new `{{ period }}` variable (#2876)
*  NachoSoto: `Paywalls`: disabled `PaywallViewMode`s for now (#2874)
* NachoSoto: `Paywalls`: added new `defaultPackage` configuration
(#2871)
*  NachoSoto: `Paywalls`: fixed tests on CI (#2872)
* NachoSoto: `Paywalls`: pre-fetch intro eligibility for paywalls
(#2860)
*  Andy Boedo: `Paywalls`: clean up the error view (#2873)
* NachoSoto: `Paywalls`: new API for easily displaying `PaywallView`
with just one line (#2869)
*  NachoSoto: `Paywalls`: handle missing paywalls gracefully (#2855)
* NachoSoto: `Paywalls`: temporarily disable non-fullscreen
`PaywallView`s (#2868)
* NachoSoto: `Paywalls`: added test to ensure package selection
maintains order (#2853)
* NachoSoto: `Paywalls`: added new `blurredBackgroundImage`
configuration (#2852)
*  NachoSoto: `Paywalls`: fuzzy `Locale` lookups (#2847)
*  NachoSoto: `Paywalls`: basic localization support (#2851)
*  NachoSoto: `Paywalls`: added `FooterView` (#2850)
*  NachoSoto: `Paywalls`: multi-package template (#2840)
*  NachoSoto: `Paywalls`: disable animations during unit tests (#2848)
* NachoSoto: `Paywalls`: `TrialOrIntroEligibilityChecker.eligibility(for
packages:)` (#2846)
* NachoSoto: `Paywalls`: added new `total_price_and_per_month` variable
(#2845)
*  NachoSoto: `Paywalls`: extracted `PurchaseButton` (#2839)
*  NachoSoto: `Paywalls`: extracted `IntroEligibilityStateView` (#2837)
* NachoSoto: `Paywalls`: support for multiple `PaywallViewMode`s (#2834)
* NachoSoto: `Paywalls`: add support for multiple images in template
configuration (#2832)
* NachoSoto: `Paywalls`: extracted configuration processing into a new
`TemplateViewConfiguration` (#2830)
* NachoSoto: `Paywalls`: improved support for dynamic type with
snapshots (#2827)
* NachoSoto: `Paywalls`: disable `macOS`/`macCatalyst`/`watchOS` for now
(#2821)
* NachoSoto: `Paywalls`: using new color information in template (#2823)
*  NachoSoto: `Paywalls`: set up CI tests and API Tester (#2816)
*  NachoSoto: `Paywalls`: added support for decoding colors (#2822)
* NachoSoto: `Paywalls`: ignore empty strings in
`LocalizedConfiguration` (#2818)
*  NachoSoto: `Paywalls`: updated `PaywallData` field names (#2817)
*  NachoSoto: `Paywalls`: added support for purchasing (#2812)
* NachoSoto: `Paywalls`: added tests for `PackageType` filtering (#2810)
* Andy Boedo: `Paywalls`: changed variable handling to use Swift `Regex`
(#2811)
*  NachoSoto: `Paywalls`: added `price` variable (#2809)
*  NachoSoto: `Paywalls`: determine intro eligibility (#2808)
*  NachoSoto: `Paywalls`: added header image to configuration (#2800)
*  NachoSoto: `Paywalls`: added `packages` to configuration (#2798)
* NachoSoto: `Paywalls`: add support for displaying
`StoreProductDiscount`s (#2796)
*  NachoSoto: `Paywalls`: added support for variables (#2793)
* NachoSoto: `Paywalls`: using `PaywallData` and setting up basic
template loading (#2781)
*  NachoSoto: `Paywalls`: initial configuration types (#2780)
*  NachoSoto: `Paywalls`: initial `RevenueCatUI` target setup (#2776)

</details>

### Other Changes

* `Debug`: add `Offering` metadata to debug screen (#3137) via NachoSoto
(@NachoSoto)
* `TestStoreProduct`: new `locale` parameter (#3134) via NachoSoto
(@NachoSoto)
* `Integration Tests`: fixed more flaky failures (#3218) via NachoSoto
(@NachoSoto)

---------

Co-authored-by: NachoSoto <ignaciosoto90@gmail.com>
Co-authored-by: NachoSoto <NachoSoto@users.noreply.github.com>

### Motivation

Fixes #4034

`PurchaseHandler` was being cleared/reset when a paywall was being
rendered (ex: if an overlay was applied to it)

### Description

- Restores `PurchaseHandler` back to being a `@StateObject` from #3187
- `checkForConfigurationConsistency()` has a few changes
- Takes a `PurchaseHandler` as a parameter so it doesn't try to access
the `StateObject`
- This was fixes the purple Xcode warning of being access wrongly by it
being a `StateObject` again
- Removes `mutating` keyword and returns an `NSError?` which it now sets
in the constructor

### Demo

#### Using RevenueCat


https://github.com/RevenueCat/purchases-ios/assets/401294/7e6430ca-6243-49ad-b7c0-8a90d90894f8

#### Using MyApp


https://github.com/RevenueCat/purchases-ios/assets/401294/829f12c3-a11a-4952-883c-7ae7addd9c1d

### Motivation

Fixes #4034

`PurchaseHandler` was being cleared/reset when a paywall was being
rendered (ex: if an overlay was applied to it)

### Description

- Restores `PurchaseHandler` back to being a `@StateObject` from #3187
- `checkForConfigurationConsistency()` has a few changes
- Takes a `PurchaseHandler` as a parameter so it doesn't try to access
the `StateObject`
- This was fixes the purple Xcode warning of being access wrongly by it
being a `StateObject` again
- Removes `mutating` keyword and returns an `NSError?` which it now sets
in the constructor

### Demo

#### Using RevenueCat


https://github.com/RevenueCat/purchases-ios/assets/401294/7e6430ca-6243-49ad-b7c0-8a90d90894f8

#### Using MyApp


https://github.com/RevenueCat/purchases-ios/assets/401294/829f12c3-a11a-4952-883c-7ae7addd9c1d