feat: expose init swizzling option to ObjC consumers

Mirror enableUIViewControllerInitSwizzling in the SentryObjC wrapper, so
apps using the pure Objective-C interface can enable it too. Regenerate
the public API surface for the objc targets.

Add this PR's number to the changelog entry, which Danger requires
alongside the issue's.

Author: philipphofmann

CHANGELOG.md

@@ -7,7 +7,7 @@
 
 ### Features
 
-- Add experimental `options.experimental.enableUIViewControllerInitSwizzling` (disabled by default) that defers `UIViewController` performance swizzling to first instantiation instead of eagerly discovering and swizzling all subclasses at SDK start. This avoids realizing `@available`-gated `UIViewController` subclasses on OS versions below their gate, which could crash the app on start (#8548).
+- Add experimental `options.experimental.enableUIViewControllerInitSwizzling` (disabled by default) that defers `UIViewController` performance swizzling to first instantiation instead of eagerly discovering and swizzling all subclasses at SDK start. This avoids realizing `@available`-gated `UIViewController` subclasses on OS versions below their gate, which could crash the app on start (#8625, #8548).
 
 ### Breaking Changes
 

GH-8548-HANDOFF.md

@@ -256,22 +256,32 @@ Repo gotchas learned while wiring it up, worth knowing independently:
   `ERR Suite failed. error="User Abandoned Test -- User terminated"` means **timeout**, not assertion
   failure.
 
-## Deferred (non-blocking, still open)
+## Ready-for-review checklist
 
-1. **Changelog is missing the PR number** — Danger fails with "Please consider adding a changelog
-   entry". The entry exists under `## Unreleased` → Features but omits `(#8625)`, which Danger
-   requires. One-line fix.
-2. **ObjC mirror missing** — `enableUIViewControllerInitSwizzling` is absent from
+Done:
+
+1. **Changelog** — entry under `## Unreleased` → Features now carries `(#8625, #8548)`. Danger requires
+   this PR's own number, not just the issue's.
+2. **ObjC mirror** — `enableUIViewControllerInitSwizzling` added to
    `Sources/SentryObjC/Public/SentryObjCExperimentalOptions.h` and
-   `Sources/SentryObjCCompat/SentryObjCExperimentalOptions.swift`, so pure-ObjC consumers can't enable
-   the fix. Note `enableStandaloneAppStartTracing` is **also** unmirrored, so there is precedent either
-   way; decide whether to mirror just this one, both, or neither (and document the reason).
+   `Sources/SentryObjCCompat/SentryObjCExperimentalOptions.swift`, so pure-ObjC consumers can enable
+   it. `sdk_api*.json` regenerated, including the `objc` and `objccompat` surfaces.
+   (`enableStandaloneAppStartTracing` remains unmirrored — pre-existing, out of scope here.)
 3. **`run-full-ci` label** — applied.
-4. **Delete this handoff file before merge** — it is agent scratch, not maintainer docs. The durable
-   content lives in the PR description and code comments.
-   Also close (don't merge) **PR #8667**, the stacked iOS 15 probe.
+4. **Public API surface** — regenerated via `make generate-public-api`; the `api-stability` check
+   diffs it against the committed files.
+
+Still open:
+
 5. **Don't close #8548 with this PR** — the option defaults to **off**, so default-configuration users
    remain exposed. Reference the issue; close it when the default flips.
+6. **Delete this handoff file before merge** — it is agent scratch, not maintainer docs. The durable
+   content lives in the PR description and code comments. Keeping it for now, on request.
+   Also close (don't merge) **PR #8667**, the stacked iOS 15 probe.
+7. **Known-flaky CI, not caused by this PR** — `Collect App Metrics` and the `Release` gate that
+   depends on it failed with SauceLabs session errors (`Unable to find session with requested ID`,
+   WebDriverAgent session drops) on the perf-test apps, which this PR doesn't touch. Every substantive
+   job in that run passed. Worth one re-run once SauceLabs is less congested.
 
 ## How to pick this up
 

Sources/SentryObjC/Public/SentryObjCExperimentalOptions.h

@@ -21,6 +21,27 @@ NS_ASSUME_NONNULL_BEGIN
 /// When enabled, the SDK uses a more efficient mechanism for detecting watchdog terminations.
 @property (nonatomic) BOOL enableWatchdogTerminationsV2;
 
+/**
+ * Reduces SDK start overhead by swizzling each @c UIViewController subclass lazily, the first time
+ * an instance of it is created, instead of eagerly discovering and swizzling every subclass when
+ * the SDK starts.
+ *
+ * By default, the SDK scans loaded binary images for all @c UIViewController subclasses at start
+ * and swizzles them up front. This realizes every subclass to inspect it, so the cost grows with
+ * the number of view controllers in the app - including ones it never uses - and it realizes
+ * @c \@available -gated subclasses that reference newer-framework types, which crashes on OS
+ * versions below the gate.
+ *
+ * With this option, only classes the app actually instantiates are touched: a class that can't
+ * exist on the current OS is never instantiated, so it's never realized or swizzled. This cuts
+ * start-up work and avoids the gated-subclass crash while producing the same @c ui.load
+ * auto-instrumentation transactions.
+ *
+ * @warning This is an experimental feature and is therefore disabled by default.
+ * @see https://github.com/getsentry/sentry-cocoa/issues/8548
+ */
+@property (nonatomic) BOOL enableUIViewControllerInitSwizzling;
+
 /// Initializes experimental options with default values.
 - (instancetype)init;
 

Sources/SentryObjCCompat/SentryObjCExperimentalOptions.swift

@@ -26,6 +26,11 @@ import Foundation
         get { wrapped.enableWatchdogTerminationsV2 }
         set { wrapped.enableWatchdogTerminationsV2 = newValue }
     }
+
+    @objc public var enableUIViewControllerInitSwizzling: Bool {
+        get { wrapped.enableUIViewControllerInitSwizzling }
+        set { wrapped.enableUIViewControllerInitSwizzling = newValue }
+    }
 }
 
 // swiftlint:enable missing_docs

sdk_api_objc.json

@@ -2089,6 +2089,13 @@
     "returnType": "BOOL",
     "instance": true
   },
+  {
+    "kind": "ObjCMethodDecl",
+    "name": "enableUIViewControllerInitSwizzling",
+    "parent": "SentryObjCExperimentalOptions",
+    "returnType": "BOOL",
+    "instance": true
+  },
   {
     "kind": "ObjCMethodDecl",
     "name": "enableUIViewControllerTracing",
@@ -5883,6 +5890,13 @@
     "returnType": "void",
     "instance": true
   },
+  {
+    "kind": "ObjCMethodDecl",
+    "name": "setEnableUIViewControllerInitSwizzling:",
+    "parent": "SentryObjCExperimentalOptions",
+    "returnType": "void",
+    "instance": true
+  },
   {
     "kind": "ObjCMethodDecl",
     "name": "setEnableUIViewControllerTracing:",
@@ -9126,6 +9140,12 @@
     "parent": "SentryObjCOptions",
     "type": "BOOL"
   },
+  {
+    "kind": "ObjCPropertyDecl",
+    "name": "enableUIViewControllerInitSwizzling",
+    "parent": "SentryObjCExperimentalOptions",
+    "type": "BOOL"
+  },
   {
     "kind": "ObjCPropertyDecl",
     "name": "enableUIViewControllerTracing",

sdk_api_objc_v10.json

@@ -2202,6 +2202,13 @@
     "returnType": "BOOL",
     "instance": true
   },
+  {
+    "kind": "ObjCMethodDecl",
+    "name": "enableUIViewControllerInitSwizzling",
+    "parent": "SentryObjCExperimentalOptions",
+    "returnType": "BOOL",
+    "instance": true
+  },
   {
     "kind": "ObjCMethodDecl",
     "name": "enableUIViewControllerTracing",
@@ -6115,6 +6122,13 @@
     "returnType": "void",
     "instance": true
   },
+  {
+    "kind": "ObjCMethodDecl",
+    "name": "setEnableUIViewControllerInitSwizzling:",
+    "parent": "SentryObjCExperimentalOptions",
+    "returnType": "void",
+    "instance": true
+  },
   {
     "kind": "ObjCMethodDecl",
     "name": "setEnableUIViewControllerTracing:",
@@ -9468,6 +9482,12 @@
     "parent": "SentryObjCOptions",
     "type": "BOOL"
   },
+  {
+    "kind": "ObjCPropertyDecl",
+    "name": "enableUIViewControllerInitSwizzling",
+    "parent": "SentryObjCExperimentalOptions",
+    "type": "BOOL"
+  },
   {
     "kind": "ObjCPropertyDecl",
     "name": "enableUIViewControllerTracing",